Bounceback By Providers Collapse All

AppRiver
554 5.0.0 message is too large for the receiving server
Your message is too large, if you have an attachment you will need to remove it and retry the message.
BlueTie
501 Connection Refused
Your mail was rejected because the lookup of the Reverse DNS record failed. You either do not have an rDNS record or you have a generic record. Your rDNS record for your IP should have the sending domain. You can check your record with our rDNS Lookup tool.
550 Sender Refused
You must have a valid A or MX record for the sending domain. You can use our tools to check for the records and see if there is a problem with the DNS.
550 Recipient Unknown
This message means the user does not exist on the mail system. The email address is either misspelled or not in service. If it is part of your mailing list, you should remove that user to protect your reputation.
552 Message Size Exceeded
The BlueTie system has a limit of 25MB per message. You need to reduce message size. Keep in mind that minimal size gets added when you send an email, so even if it shows 14.7MB when you send it, the message could end up bigger when it actually sends.
554 BL0001
Your email was blocked because it is on the Cloudmark Sender Intelligence (CSI) Blocklist.
554 BL0002
Your email was blocked because it is on the Spamcop Blocklist.
554 BL0003
Your email was blocked because it is on the Return Path Reputation Network Blocklist.
554 BL0004
BlueTie has blocked your email based on their in-house blocklist. You will need to contact BlueTie in order to be removed.
554 BL0005
This error means your message was blocked because the mail server sending your message has been blocked due to violating BlueTie's policies, such as sending to invalid recipients, too many open connections, and invalid "mail from" domains.
Comcast
BL000000
This bounceback means that Comcast considers this message spam due to IP reputation. Keep in mind that you are unlikely to get an actual response from them, regardless if they remove you from the blocklist or not. It can also take a long time before they take any action.
BL000001
Your email was blocked by Comcast because it is on the Spamhaus Zen Blocklist. You can request delisting at http://www.spamhaus.org/lookup/
BL000010
Your email was blocked by Comcast because it is on the Cloudmark Sender Intelligence (CSI) Blocklist. You can request removal at http://csi.cloudmark.com/reset-request/
BL000011
Your email was blocked by Comcast because it is on both the Spamhaus Zen and Cloudmark Sender Intelligence (CSI) blocklists.
BL000100
Your email was blocked by Comcast because it is on the Return Path Reputation Network Blocklist.
BL000101
Your email was blocked by Comcast because it is on both the Spamhaus Zen and Return Path Reputation Network blocklists.
BL000110
Your email was blocked by Comcast because it is on the Cloudmark Sender Intelligence (CSI) and Return Path Reputation Network blocklists.
BL000111
Your email was blocked by Comcast because it is on the Spamhaus Zen, Cloudmark Sender Intelligence (CSI), and Return Path Reputation Network blocklists.
DM000001
Your email was blocked by Comcast because of the domain's published DMARC policy. If this is a legitmate message, you should check the domain's DMARC, SPF, and DKIM records to ensure that they include the sending source.
ES000001
Your email was blocked by Comcast because the sending IP is identified as a dynamic/residential IP address. Typically, this means a misconfigured email client, but if this is a static IP address, you should contact whomever leased you the IP address and ask them to resolve the problem. They need to ensure it is not still listed as part of their dynamic space. This can be a laborious process, as most of the initial technicians you speak to will not be able to do this and might not be familiar with IP management. You should also ask them to enable a PTR record for the IP that should include your domain name, such as "email.domain.com".
RL000001
You would receive this bounceback if you are sending too much email too quickly to Comcast. The number of recipients per hour you can send is based on your Senderscore Reputation. https://drive.google.com/file/d/1nDWZozFImgwAKzbOkwZYFdf_tts0i8Lv/view?usp=sharing
RL000002
Your IP's reputation is affecting the rate you can send email. This is often because your IP has just recently started sending mail to Comcast. You will want to 'warm up' the IP by sending smaller amounts of mail daily and slowly increasing it each day.
RL000003
Comcast has limited the amount of email that can be sent from this IP due to the previous volume and quality of messages from this IP. There does not seem to be any way to contest this with Comcast, but you could try their blocklist removal form.
421 Too many sessions opened
Your mail server is opening too many connections to Comcast. You may only have 25 simultaneous connections per IP. You should configure your mail server's maximum number of connections so it does not exceed this limit, or make sure it is properly closing connections.
421 Reverse DNS failure
Your mail was rejected because the lookup of the Reverse DNS Record failed. This could be a temporary error, but you should do an rDNS lookup on your IP address to be sure because it could mean there is a DNS problem that would affect your email delivery.
421 Try again later
This is an error from Comcast that does not have a specific reason, but they indicate that it is a temp error and you should try sending the message again.
452 Too many emails sent on this session
Comcast has a limit of 1,000 emails per session. If you are getting this error, you likely need to configure your mail server to close the connection and open a new one to send more than 1,000 emails.
452 Too many recipients for message
Comcast has a limit of 100 recipients per email. You need to reduce the number of recipients per email.
550 Not our customer
This means the user does not exist in the Comcast system. The email address is either misspelled or not in service. If this is part of a mailing list, you should remove that user to protect your reputation with Comcast.
550 Too many invalid recipients
If your email includes too many recipients who are not valid in the Comcast system, they reject the message for all recipients. You should check the list of recipients and resend.
550 Invalid sender domain
You must have a valid A or MX record for the sending domain. You can use our tools to check for the records and see if there is a problem with the DNS.
550 Account not available
This error means the mailbox is not available for some reason. This is a perm fail and you should not keep trying to send to this address.
552 Message size exceeded
Comcast has a limit of 15MB per message. You need to reduce message size. Keep in mind that minimal size gets added when you send an email, so even if it shows 14.7MB when you send it, the message could end up bigger when it actually sends.
554 PTR lookup failure
Your mail was rejected because the lookup of the Reverse DNS record failed. You either do not have an rDNS record or you have a generic record. Your rDNS record for your IP should have the sending domain. You can check your record with our rDNS Lookup tool.
BL001000
Your email could not be delivered because your email provider is listed on the Vade Threat List (VTL). VTL is a list of IP addresses which have been detected as sending spam. Comcast uses this list to protect its subscribers from receiving spam.
BL001001
Your email could not be delivered because your email provider is listed on the Vade Threat List (VTL), as well as the Spamhaus Zen Blocklist. These are lists of IP addresses which have been detected as sending spam. Comcast uses this list to protect its subscribers from receiving spam.
BL001010
Your email could not be delivered because your email provider is listed on the Vade Threat List (VTL), as well as the Cloudmark Sender Intelligence (CSI) Blocklist. These are lists of IP addresses which have been detected as sending spam. Comcast uses this list to protect its subscribers from receiving spam.
BL001011
Your email could not be delivered because your email provider is listed on the Vade Threat List (VTL), Spamhaus Zen, and Cloudmark Sender Intelligence (CSI) blocklists. These are lists of IP addresses which have been detected as sending spam. Comcast uses this list to protect its subscribers from receiving spam.
BL001100
Your email could not be delivered because your email provider is listed on the Vade Threat List (VTL), as well as the Return Path Reputation Network Blocklist. These are lists of IP addresses which have been detected as sending spam. Comcast uses this list to protect its subscribers from receiving spam.
BL001101
Your email could not be delivered because your email provider is listed on the Vade Threat List (VTL), Spamhaus Zen, and Return Path Reputation Network blocklists. These are lists of IP addresses which have been detected as sending spam. Comcast uses this list to protect its subscribers from receiving spam.
BL001110
Your email could not be delivered because your email provider is listed on the Vade Threat List (VTL), Cloudmark Sender Intelligence (CSI), and Return Path Reputation Network blocklists. These are lists of IP addresses which have been detected as sending spam. Comcast uses this list to protect its subscribers from receiving spam.
BL001111
Your email could not be delivered because your email provider is listed on the Vade Threat List (VTL), Spamhaus Zen, Cloudmark Sender Intelligence (CSI), and Return Path Reputation Network blocklists. These are lists of IP addresses which have been detected as sending spam. Comcast uses this list to protect its subscribers from receiving spam.
ES000010
You have been blocked from sending to the Comcast network because they have determined that you are sending email from dynamic/residential IP space. Comcast does not allow residential/dynamic IP addresses to directly connect to their email servers. In most cases, Comcast will classify your email server's IP address as dynamic if the reverse DNS does not comply with standard static naming conventions.
Cox
CXBL
Cox has detected spamlike behavior from your IP address. You will need to send an unblock request. Keep in mind, this can take time before they take any action and they likely will not contact you to tell you the result.
CXTHRT
This message is specific to Cox email users trying to send a message. It means your account has been blocked due to suspicious activity. You should reset your password.
CXMJ
This message is specific to Cox email users trying to send a message. It means your account has been blocked due to suspicious activity by the primary user on the Cox account. You should reset your password.
CXDNS
Your mail was rejected because the lookup of the Reverse DNS record failed. You either do not have an rDNS record or you have a generic record. Your rDNS record for your IP should have the sending domain. You can check your record with our rDNS Lookup tool.
CXSNDR
Your email was rejected by Cox because of a DMARC, DKIM, or SPF problem. If you have the headers of the message (sometimes included with the bounce), you can use our Header Analyzer tool to check the message. If not, try using the same sending email system with our Email Deliverability tool.
CXSMTP
Your email was rejected because Cox could not determine if it was sent by a legitimate sender. Try using our SMTP and Email Deliverability tools to find any problems.
CXCNCT
Cox limits concurrent connections from a mail server to 10. You need to configure your system to only allow a maximum of 10 connections or to properly close connections.
CXMXRT
This error is due to sending messages to too many email recipients too quickly. Cox does not provide specific details on how many recipients it allows per hour/day/etc., but you should wait and try sending the message again.
CDRBL
The sending IP address has been blocked by Cox for a temporary period up to 24 hours due to spamlike behavior. You should check your IP in our Blocklist Tool or look at blocklist monitoring options.
IPBL0001
Cox has blocked your IP address because it is on the Spamhaus Zen Blocklist.
IPBL0010
Cox has blocked your IP address because it is on the Return Path Reputation Network Blocklist.
IPBL0100
Cox has blocked your IP address because it is on the ivmSIP Blocklist.
IPBL0011
Your email was blocked by Cox because it is on both the Spamhaus Zen and Return Path Reputation Network blocklists.
IPBL0101
Your email was blocked by Cox because it is on both the Spamhaus Zen and ivmSIP blocklists.
IPBL0110
Your email was blocked by Cox because it is on both the Return Path Reputation Network and ivmSIP blocklists.
IPBL0111
Your email was blocked by Cox because it is on the Spamhaus Zen, Return Path Reputation Network, and ivmSIP blocklists.
IPBL1000
Cox has blocked your IP address because it is on the Cloudmark Sender Intelligence (CSI) Suspect/CSI Global Blocklist.
IPBL1001
Your email was blocked by Cox because it is on the Cloudmark Sender Intelligence (CSI) and Spamhaus Zen blocklists.
IPBL1010
Your email was blocked by Cox because it is on the Cloudmark Sender Intelligence (CSI) and Return Path Reputation Network blocklists.
IPBL1011
Your email was blocked by Cox because it is on the Cloudmark Sender Intelligence (CSI), Spamhaus Zen, and Return Path Reputation Network blocklists.
IPBL1100
Your email was blocked by Cox because it is on the Cloudmark Sender Intelligence (CSI) and ivmSIP blocklists.
IPBL1101
Your email was blocked by Cox because it is on the Cloudmark Sender Intelligence (CSI), Spamhaus Zen, and ivmSIP blocklists.
IPBL1110
Your email was blocked by Cox because it is on the Cloudmark Sender Intelligence (CSI), Return Path Reputation Network, and ivmSIP blocklists.
IPBL1111
Your email was blocked by Cox because it is on the Cloudmark Sender Intelligence (CSI), Spamhaus Zen, Return Path Reputation Network, and ivmSIP blocklists.
IPBL00001
Cox has blocked your IP address because it is on the Spamhaus Zen Blocklist.
URLBL011
Cox blocked this message because a URL in the email was listed on the SURBL and Spamhaus blocklists.
URLBL101
Cox blocked this message because a URL in the email was listed on the SURBL and ivmURI blocklists.
URLBL110
Cox blocked this message because a URL in the email was listed on the Spamhaus and ivmURI blocklists.
URLBL1001
Cox blocked this message because a URL in the email was listed on the Spamhaus Blocklist.
421 ESMTP server temporarily not available
Cox email systems are experiencing a problem. Try sending the message again later.
421 too many sessions
Cox limits concurrent connections to five (5). Your message was rejected because your mail server had more than five (5) connections open. You should configure your mail server's maximum number of connections so it does not exceed this limit or make sure it is properly closing connections.
554 ESMTP no data before greeting
Your mail server attempted to send message data before properly sending a greeting according to RFC 5321. You need to ensure that your mail server is properly configured.
554 rejected - no rDNS
Your mail was rejected because the lookup of the Reverse DNS record failed. You either do not have an rDNS record or you have a generic record. Your rDNS record for your IP should have the sending domain. You can check your record with our rDNS Lookup tool.
554 too many bad commands
This error is specific to Cox email users. It means the email client is either misconfigured or is using a wrong password.
421 DNS check failure
Your mail was rejected because the lookup of the Reverse DNS Record failed. This could be a temporary error, but you should do an rDNS lookup on your IP address to be sure because it could mean there is a DNS problem that would affect your email delivery.
452 requested action aborted
Cox has refused this message because the sending mail server tried sending over 100 messages in a single connection. Your mail server needs to properly close connections and open a new one to send further messages.
550 sender rejected
You must have a valid A or MX record for the sending domain. You can use our tools to check for the records and see if there is a problem with the DNS.
552 attachment extension is forbidden
Cox does not allow the following file types: .shb, .shs, .vbe, .vbs, .wsc, .wsf, .wsh, .pif, .msc, .msi, .msp, .reg, .sct, .bat, .chm, .isp, .cpl, .js, .jse, .scr, .exe.
452 too many invalid recipients
If your email includes too many recipients who are not valid emails on the Cox system, they reject the message for all recipients. You should check the list of recipients.
452 message threshold exceeded
This error is because the sending mail server has sent too much email to the Cox email system. The system is temporarily banned from sending further messages. You should try the message again in 24 hours. Cox does not provide specific numbers on how many messages you are allowed to send.
550 recipient rejected
The intended recipient is not a valid Cox email account. Ensure that your mailing list is up-to-date with verified recipient email addresses.
Generic
5.7.1 Spam or virus
A 5.7.1 message indicates that something in the email was identified as dangerous and likely contains spam, a virus, or the sender is blocked. This error generally occurs for two reasons: 1. An individual PC is infected with malware and sending malicious messages. This tends to be characterized by getting several of these bounces for messages the user does not recognize as having sent. 2. An attachment was included that violated the recipient's email policies either by file type or by being encrypted. It does not necessarily mean the email server itself it blocked, but often, if the messages continue (i.e., the user has malware), then it will typically cause email problems to that recipient for the entire email server.
5.4.7 Delivery expired
A 5.4.7 message - Delivery expired (message too old) - is typically a message from your mail system, not the recipient's server. It is often related to a Cisco appliance. This error indicates the message sat in the outbound delivery queue for too long. Unfortunately, it does not provide a specific reason, but usually this means the recipient system would not accept the message. This can be for many different reasons. We recommend checking the following: 1. Look at the message subject and sender. Are they someone who would have sent this email? If it does not seem likely, you might have a spam outbreak on your hands, which is why the recipient system would not accept the message. Check your outbound mail queues to see if there are more messages queuing up and stop outbound email if it looks like a spam outbreak. 2. Check if any mail is going out at all. Test to a Gmail or other outside email address. 3. Run a blacklist check to see if your IP address is listed. 4. If you are at a loss, you can sign up for our Managed Services product, which provides an email delivery specialist who can help you setup DMARC and other technologies to help improve your email delivery.
DNS Soft Error
If you get a "DNS Soft Error" message, it indicates that somewhere there is a problem looking up the DNS record to delivery email. It could be on your end or the recipient's end. The first thing you will need to do is figure out whose problem it is: 1. Run an MX Lookup on the recipient domain. If the MX records return, their DNS is likely working. 2. Use the link on our results to run an SMTP test on each of the MX records returned. If the test succeeds, then there is a good chance the problem lies elsewhere or was a temporary issue. The next place to look is on your mail system. You should try an NSLookup or DIG on the MX record for the recipient domain. If that test fails, you have a DNS problem on your system. You could try flushing your DNS to see if that works. If the DNS test succeeds, you should probably try sending the message to see if it was a temporary issue.
5.4.1 Recipient address rejected
The recipient's mail system could not verify the address. Check the address for spelling and accuracy. If this email is part of a mailing list, you might want to remove it to protect your reputation.
Gmail
501 5.5.4
Gmail: HELO/EHLO argument is invalid. For more information, see https://support.google.com/mail/answer/6386757?visit_id=637393351314081104-2641074270&p=helo&rd=1
504 5.7.4
Gmail: Unrecognized Authentication Type.
503 5.5.1
Gmail: EHLO/HELO first.
421 4.4.5
Gmail: Server busy; try again later.
421 4.7.0
Gmail: IP not in whitelist for RCPT domain, closing connection.
421 4.7.0
Gmail: Our system has detected an unusual rate of unsolicited mail originating from your IP address. To protect our users from spam, mail sent from your IP address has been temporarily blocked. See Prevent mail to Gmail users from being blocked or sent to spam.
421 4.7.0
Gmail: Temporary System Problem. Try again later.
421 4.7.0
Gmail: TLS required for RCPT domain, closing connection.
421 4.7.0
Gmail: Try again later, closing connection. This usually indicates a Denial of Service (DoS) for the SMTP relay at the HELO stage.
450 4.2.1
Gmail: The user you are trying to contact is receiving mail too quickly. Please resend your message at a later time. If the user is able to receive mail at that time, your message will be delivered. For more information, see Limits for sending & getting mail.
450 4.2.1
Gmail: The user you are trying to contact is receiving mail at a rate that prevents additional messages from being delivered. Please resend your message at a later time. If the user is able to receive mail at that time, your message will be delivered. For more information, see Limits for sending & getting mail.
450 4.2.1
Gmail: Peak SMTP relay limit exceeded for customer. This is a temporary error. For more information on SMTP relay limits, please contact your administrator or see SMTP relay service error messages.
451 4.3.0
Gmail: Mail server temporarily rejected message.
451 4.3.0
Gmail: Multiple destination domains per transaction is unsupported. Please try again.
451 4.4.2
Gmail: Timeout - closing connection.
451 4.5.0
Gmail: SMTP protocol violation, see RFC 2821.
452 4.2.2
Gmail: The email account that you tried to reach is over quota. Please direct the recipient to Clear Google Drive space & increase storage.
452 4.5.3
Gmail: Domain policy size per transaction exceeded, please try this recipient in a separate transaction. This message means the email policy size (size of policies, number of policies, or both) for the recipient domain has been exceeded.
452 4.5.3
Gmail: Your message has too many recipients. For more information regarding Google's sending limits, see Limits for sending & getting mail.
454 4.5.0
Gmail: SMTP protocol violation, no commands allowed to pipeline after STARTTLS, see RFC 3207.
454 4.7.0
Gmail: Cannot authenticate due to temporary system problem. Try again later.
454 5.5.1
Gmail: STARTTLS may not be repeated.
501 5.5.2
Gmail: Cannot Decode response.
502 5.5.1
Gmail: Too many unrecognized commands, goodbye.
502 5.5.1
Gmail: Unimplemented command.
502 5.5.1
Gmail: Unrecognized command.
503 5.5.1
Gmail: MAIL first.
503 5.5.1
Gmail: RCPT first.
503 5.7.0
Gmail: No identity changes permitted.
530 5.5.1
Gmail: Authentication Required. For more information, see Can't sign in to your Google Account.
530 5.7.0
Gmail: Must issue a STARTTLS command first.
535 5.5.4
Gmail: Optional Argument not permitted for that AUTH mode.
535 5.7.1
Gmail: Application-specific password required. For more information, see Sign in using App Passwords.
535 5.7.1
Gmail: Please log in with your web browser and then try again. See Check Gmail through other email platforms.
535 5.7.1
Gmail: Username and Password not accepted. For more information, see Can't sign in to your Google Account.
550 5.1.1
Gmail: The email account that you tried to reach does not exist. Please try double-checking the recipient's email address for typos or unnecessary spaces. For more information, see Fix bounced or rejected emails.
550 5.2.1
Gmail: The email account that you tried to reach is disabled.
550 5.2.1
Gmail: The user you are trying to contact is receiving mail at a rate that prevents additional messages from being delivered. For more information, see Limits for sending & getting mail.
550 5.4.5
Gmail: Daily sending quota exceeded. For more information, see Email sending limits.
550 5.4.5
Gmail: Daily SMTP relay limit exceeded for user. For more information on SMTP relay sending limits please contact your administrator or see SMTP relay service error messages.
550 5.7.0
Gmail: Mail relay denied.
550 5.7.0
Gmail: Mail Sending denied. This error occurs if the sender account is disabled or not registered within your Google Workspace domain.
550 5.7.1
Gmail: Email quota exceeded.
550 5.7.1
Gmail: Invalid credentials for relay.
550 5.7.1
Gmail: Our system has detected an unusual rate of unsolicited mail originating from your IP address. To protect our users from spam, mail sent from your IP address has been blocked. Review Prevent mail to Gmail users from being blocked or sent to spam.
550 5.7.1
Gmail: Our system has detected that this message is likely unsolicited mail. To reduce the amount of spam sent to Gmail, this message has been blocked. For more information, see Why has Gmail blocked my messages?
550 5.7.1
Gmail: The IP you're using to send mail is not authorized to send email directly to our servers. Please use the SMTP relay at your service provider instead. For more information, see 'The IP you're using to send email is not authorized...'.
550 5.7.1
Gmail: The user or domain that you are sending to (or from) has a policy that prohibited the mail that you sent. Please contact your domain administrator for further details. For more information, see Sorry, a policy is in place that prevents your message from being sent.
550 5.7.1
Gmail: Unauthenticated email is not accepted from this domain.
550 5.7.1
Gmail: Daily SMTP relay limit exceeded for customer. For more information on SMTP relay sending limits please contact your administrator or see SMTP relay service error messages.
552 5.2.2
Gmail: The email account that you tried to reach is over quota.
552 5.2.3
Gmail: Your message exceeded Google's message size limits. For more information, see Send attachments with your Gmail message.
553 5.1.2
Gmail: We weren't able to find the recipient domain. Please check for any spelling errors, and make sure you didn't enter any spaces, periods, or other punctuation after the recipient's email address.
554 5.6.0
Gmail: Mail message is malformed. Not accepted.
554 5.6.0
Gmail: Message exceeded 50 hops, this may indicate a mail loop.
554 5.7.0
Gmail: Too Many Unauthenticated commands.
555 5.5.2
Gmail: Syntax error.
GMX
4xy Rate limit reached
GMX: Too many messages have been received in a short period of time. Please try again in a few hours and reduce the sending rate.
4xy Administrative reject
GMX: Your email was temporarily rejected due to a general system overload.
5xy Reject due to SPF policy
GMX: The email was rejected because it was sent from a server that is not included in the domain owner's SPF record. This usually indicates that the sender address has been spoofed and that the email is spam/phishing.
5xy Syntax error in parameters or arguments
GMX: Due to an incorrect configuration, email reception has been refused. Please contact your administrator, who should correct the server configuration.
5xy Requested action not taken; mailbox unavailable
GMX: The specified recipient does not exist on GMX's systems or the recipient has not used their inbox for an extended period of time and the inbox has been temporarily disabled due to inactivity. Please check the spelling of the email address and resend.
5xy Bad DNS PTR resource record
GMX: Emails from your email server were rejected because the PTR Resource Record (PTR-RR) of your IP address does not follow GMX's guidelines. Possible reasons for this can be: The PTR-RR states that the IP address was dynamically allocated. The PTR-RR is a generic standard entry of your provider. Please allocate an independent and fully qualified domain name (Fully Qualified Domain Name - FQDN) to your email server and enter the corresponding valid PTR-RR. Individual rejection of the PTR-RR for system protection reasons.
5xy Reject due to policy restrictions (header based)
GMX: Your message will be rejected by GMX's system if any of the technical information included in the email does not meet the RFC 5321 and RFC 5322 standards, the email violates GMX's guidelines, or it is not plausible (i.e., when specifying the date). This is applicable to all emails with more than one of the following headers: BCC, CC, Date, From, Sender, Subject, To. In addition, the headers "Date, From, Sender, To" must be syntactically correct.
5xy Reject due to policy restrictions (domain based)
GMX: The email has been rejected due to GMX's current security policy. This might occur if the sender domain is known as a spam domain. To check if a domain is listed, use our Spam Analyzer tool.
5xy Reject due to policy restrictions (ip based)
GMX: The email has been rejected because it violated GMX's security policy. If a high percentage of emails are classified as spam by their filters, all messages coming from the sender's IP address will be temporarily rejected for a specific time frame.
5xy Requested mail action aborted; exceeded storage allocation
GMX: GMX was unable to deliver your email because the potential recipient does not have sufficient free space in their inbox.
5xy IP address is blocklisted
GMX: To reduce spam email reception, GMX uses popular DNSBL-lists (DNS-based Blackhole List). These lists contain dynamic IP addresses and IP addresses currently known to be spam senders. Please contact your system administrator and/or email the provider, who should check if the IP address they use is on one of these RBL (Realtime Blackhole List) and should then take the necessary steps to have the IP removed.
5xy Administrative reject
GMX: For administrative reasons, delivery of emails to GMX's systems is not permitted.
5xy Invalid DNS PTR resource record
GMX: The IP address of the email server you are using is not assigned to a domain name in the domain name service (DNS). The domain name needs to be added.
5xy Invalid DNS MX or A/AAAA resource record
GMX: The sender domain of the email server you are using has not been configured in agreement with the RFC guidelines in the domain name service (DNS). The following reasons might be responsible for this: - Neither an A- nor an MX record has been configured in the DNS for the sender domain - The MX record points to a domain name that cannot be resolved - The MX record directly points to an IP address - The MX server does not have a valid A-record, only a CNAME record
GoDaddy
421 IB101
GoDaddy's email queue is experiencing a problem. Your mail server will likely retry the message on its own. If you get a perm fail bounceback error, you will want to send the message again.
Account storage limit secureserver.net
The recipient's mailbox is full. They will not be able to receive your message until they clear out some messages.
Account does not exist secureserver.net
The recipient's mail system could not verify the address. Check the address for spelling and accuracy. If this email is part of a mailing list, you might want to remove it to protect your reputation.
Account disabled secureserver.net
The account has been disabled. It can no longer accept mail.
Delivery timeout secureserver.net
This is likely an issue related to the recipient's mail server. You should wait and try sending the message again. If you get another bounceback, they are likely either experiencing a major issue or their server is down permanently.
This message is looping 5.4.6
The recipient likely has a forward setup that is causing the message to loop. You should not resend the message until the recipient fixes the issue.
550 Recipient not found secureserver.net
The recipient's mail system could not verify the address. Check the address for spelling and accuracy. If this email is part of a mailing list, you might want to remove it to protect your reputation.
451 Sorry, I was unable to establish an SMTP connection
The recipient you tried to send a message to could not receive the message. Either the recipient is invalid or their provider has blocked their address. It is not recommended that you send to this address again.
535 IB401
This message was rejected because the sending mail server attempted to authenticate. This is a mail server configuration issue that needs to be addressed as it should not attempt to authenticate on inbound mail.
550 IB501
The "from" address was blank and rejected because blank "from" addresses are not allowed. Check your email client to be sure you have configured it correctly. If this is a calendar invite or auto-reply, you should check the configuration to include a "from" address.
550 IB502
The "from" address is an IP address. It must be a valid email address.
550 IB506
The domain in the "from" address either did not have MX records or there was a problem with the DNS lookup of the MX records. You can use our MX Record Lookup tool to check.
550 IB508
The sending email's domain has an SPF record that does not authorize the sending mail server to send messages for that domain. The SPF record will need to be corrected for this message to go through. You can check the SPF record with our SPF Record Lookup tool.
421 IB108
Your mail was rejected because the lookup of the Reverse DNS record failed. You either do not have an rDNS record or you have a generic record. Your rDNS record for your IP should have the sending domain. You can check your record with our rDNS Lookup tool.
552 IB212
This message was identified as spam. If this is a mailing list, you should ensure that you are sending to users who have opted in to receive messages and that an opt out/unsubscribe option is available in the email.
552 IB705
GoDaddy has rejected the message due to content such as viruses, phishing attempts, ransomware, other malicious software, or links that have any of the above. Check that your mail server is not an open relay allowing spammers to send through your system with our SMTP tool.
452 IB605
If your email includes too many recipients who are not valid emails on the GoDaddy system, they reject the message for all recipients. You should check the list of recipients and resend.
421 IB007
Your mail server is opening too many connections to GoDaddy. You should either configure your mail server's maximum number of connections so it does not exceed this limit or make sure it is properly closing connections.
554 IB110
This IP address has attempted to send too many messages containing content judged to be spam and has been blocked for an hour. You should investigate your system to see what messages are going out that might be causing the problem before resending the message.
554 IB111
This IP address has attempted to send too many messages containing content judged to be spam and has been blocked for 24 hours. You should investigate your system to see what messages are going out that might be causing the problem before resending the message.
554 IB112
This IP address has attempted to mail too many invalid recipients and has been blocked for an hour. You should investigate your system to see what messages are going out that might be causing the problem before resending the message.
554 IB113
This IP address has attempted to mail too many invalid recipients and has been blocked for 24 hours. You should investigate your system to see what messages are going out that might be causing the problem before resending the message.
550 IB504
This IP address has reached the maximum allowed messages for that hour. You will need to wait before trying to send the message again. You might also want to check what messages your system is sending to ensure you are not affecting your reputation by sending messages too quickly.
550 IB607
You have sent to too many different recipients on the GoDaddy system. Your messages have been blocked for an hour.
554 RBL Reject
Your message is on GoDaddy's internal blocklist. There will be a link in the bounce error that you need to follow to get unblocked.
554 IB103
Your email was blocked because it is on the Cloudmark Sender Intelligence (CSI) Blocklist. You will need to request removal.
554 IB104
Your email was blocked because it is on the Spamhaus Zen Blocklist. You will need to request removal.
554 IB105
Your email was blocked because it is on the Spamhaus Zen Blocklist. You will need to request removal.
554 IB106
Your email was blocked because it is on the Spamhaus Zen Blocklist. You will need to request removal.
550 IB510
Your message has exceeded the maximum number of messages allowed for this IP address. You will need to wait before trying to send the message again.
Microsoft Office 365
5.7.350
This Microsoft Office 365 bounce message indicates that your message is spam. There can be many reasons for a message to be marked as spam and spam filters tend not to give detailed reasons as to why to prevent spammers from learning their techniques. However, there are some things that can help you try to identify the problem and improve your email delivery. You should ensure that you have DMARC enabled. A DMARC record involves enabled SPF and DKIM, which help improve your reputation with the recipient and encourage them to accept messages they may otherwise reject. No DMARC or a failure often increases the spam score. You can explore information on deploying DMARC below. You should also check our Spam Analyzer tool, which checks some common items that increase the spam score of a message.
432 4.3.2 STOREDRV.Deliver; recipient thread limit exceeded
Office 365: The recipient mailbox's ability to accept messages is being throttled because it's receiving too many messages too quickly. This is done so a single recipient's mail processing doesn't unfairly impact other recipients sharing the same mailbox database.
4.4.316 Connection refused
Office 365: Microsoft 365 or Office 365 is trying to send a message to an email server outside of Microsoft 365 or Office 365, but attempts to connect to it are failing due to a network connection issue at the external server's location.
4.4.7 Message expired
Office 365: The message in the queue has expired. The sending server tried to relay or deliver the message, but the action was not completed before the message expiration time occurred. This message can also indicate that a message header limit has been reached on a remote server, or some other protocol time-out occurred while communicating with the remote server.
4.5.3 Too many recipients
Office 365: The message has more than 200 SMTP envelope recipients from the same domain.
4.7.26 Access denied; this message is not signed
Office 365: The sending message sent over IPv6 must pass either SPF or DKIM.
4.7.500-699 Access denied, please try again later
Office 365: Suspicious activity has been detected and sending has been temporarily restricted for further evaluation.
4.7.850-899 Access denied, please try again later
Office 365: Suspicious activity has been detected on the IP in question, and it has been temporarily restricted while it is being further evaluated.
5.0.350 Generic error or x-dg-ref header is too long
Office 365: 5.0.350 is a generic catch-all error code for a wide variety of non-specific errors from the recipient's email organization. The specific x-dg-ref header is too long message is related to Rich Text formatted messages. For more information, see Fix email delivery issues for error code 550 5.0.350 in Exchange Online.
5.1.0 Sender denied
Office 365: A common cause of this NDR is when you use Microsoft Outlook to save an email message as a file, and then someone opened the message offline and replied to it. The message property only preserves the legacyExchangeDN attribute when Outlook delivers the message, and therefore the lookup could fail.
5.1.1 Bad destination mailbox address
Office 365: This failure might be caused by the following conditions:The recipient's email address was entered incorrectly by the sender. No recipient's exists in the destination email system. The recipient's mailbox has been moved and the Outlook recipient cache on the sender's computer has not updated.An invalid legacy domain name (DN) exists for the recipient's mailbox Active Directory Domain Service.
5.1.8 Access denied, bad outbound sender
Office 365: The account has been blocked for sending too much spam. Typically, this problem occurs because the account has been compromised (hacked) by phishing or malware.
5.1.10 Recipient not found
Office 365: The recipient's was not found by SMTP address lookup.
5.2.2 Submission quota exceeded
Office 365: The sender has exceeded the recipient rate limit or the message rate limit as described in Sending limits.
5.2.121 Recipient's per hour message receive limit from specific sender exceeded
Office 365: The sender has exceeded the maximum number of messages they're allowed to send per hour to a specific recipient in Exchange Online.
5.2.122 Recipient's per hour message receive limit exceeded
Office 365: The Microsoft 365 or Office 365 recipient has exceeded the number of messages they can receive per hour from all senders.
5.3.190 Journaling on-premises messages to Microsoft 365 or Office 365 not supported
Office 365: Journaling on-premises messages to Microsoft 365 or Office 365 isn't supported for this organization because they haven't turned on Journaling Archive in their settings.
5.4.1 Relay access denied
Office 365: The mail server that's generating the error doesn't accept mail for the recipient's domain. This error is generally caused by mail server or DNS misconfiguration.
5.4.6 or 5.4.14 Routing loop detected
Office 365: A configuration error has caused an email loop. 5.4.6 is generated by on-premises Exchange server (you'll see this code in hybrid environments). 5.4.14 is generated by Exchange Online.By default, after 20 iterations of an email loop, Exchange interrupts the loop and generates an NDR to the sender of the message.
5.4.300 Message expired
Office 365: The email took too long to be successfully delivered, either because the destination server never responded or the sent message generated an NDR error and that NDR could not be delivered to the original sender.
5.6.11 Invalid characters
Office 365: Your email program added invalid characters (bare line feed characters) into a message you sent.
5.7.1 Delivery not authorized
Office 365: The sender of the message is not allowed to send messages to the recipient.
5.7.1 Unable to relay
Office 365: The sending email system is not allowed to send a message to an email system where that email system is not the final destination of the message.
5.7.1 Client was not authenticated
Office 365: The sending email system did not authenticate with the receiving email system. The receiving email system requires authentication before message submission.
5.7.12 Sender was not authenticated by organization
Office 365: The sender's message is rejected because the recipient address is set up to reject messages sent from outside of its organization. Only an email admin for the recipient's organization can change this.
5.7.23 The message was rejected because of Sender Policy Framework violation
Office 365: The destination email system uses SPF to validate inbound mail, and there's a problem with your SPF configuration.
5.7.57 Client was not authenticated to send anonymous mail during MAIL FROM
Office 365: You configured an application or device to send (relay) email messages in Microsoft 365 or Office 365 using the smtp.office365.com endpoint, and there's a problem with the configuration of the application or device.
5.7.64 TenantAttribution; relay access denied
Office 365: You use an inbound connector to receive messages from your on-premises email environment, and something has changed in your on-premises environment that makes the inbound connector's configuration incorrect.
5.7.124 Sender not in allowed-senders list
Office 365: The sender doesn't have permission to send to the distribution group because the sender is not in the group's allowed-senders list. Depending how the group is set up, even the group's owner might need to be added to the allowed sender list in order to send messages to the group.
5.7.133 Sender not authenticated for group
Office 365: The recipient address is a group distribution list that is set up to reject messages sent from outside of its organization. Only an email admin for the recipient's organization or the group owner can change this.
5.7.134 Sender was not authenticated for mailbox
Office 365: The recipient address is a mailbox that is set up to reject messages sent from outside of its organization. Only an email admin for the recipient's organization can change this.
5.7.13 or 135 Sender was not authenticated for public folder
Office 365: The recipient address is a public folder that is set up to reject messages sent from outside of its organization. Only an email admin for the recipient's organization can change this.
5.7.136 Sender was not authenticated
Office 365: The recipient address is a mail user that is set up to reject messages sent from outside of its organization. Only an email admin for the recipient's organization can change this.
5.7.25 Access denied, the sending IPv6 address must have a reverse DNS record
Office 365: The sending IPv6 address must have a reverse DNS record in order to send email over IPv6.
5.7.501 Access denied, spam abuse detected
Office 365: The sending account has been banned due to detected spam activity.
5.7.502 Access denied, banned sender
Office 365: The sending account has been banned due to detected spam activity.
5.7.503 Access denied, banned sender
Office 365: The sending account has been banned due to detected spam activity.
5.7.504 Recipient address rejected: access denied
Office 365: The recipient address that you are attempting to contact is not valid.
5.7.505 Access denied, banned recipient
Office 365: The recipient that you are attempting to contact is not valid.
5.7.506 Access denied, bad HELO
Office 365: Your server is attempting to introduce itself (HELO according to RFC 821) as the server it is trying to connect to, rather than its own fully qualified domain name.
5.7.507 Access denied, rejected by recipient
Office 365: The IP that you are attempting to send from has been blocked by the recipient's organization.
5.7.508 Access denied, [$SenderIPAddress] has exceeded permitted limits within $range range
Office 365: The sender's IPv6 range has attempted to send too many messages in too short a time period.
5.7.509 Access denied, sending domain [$SenderDomain] does not pass DMARC verification
Office 365: The sender's domain in the 5322.From address does not pass DMARC.
5.7.510 Access denied, [contoso.com] does not accept email over IPv6
Office 365: The sender is attempting to transmit a message to the recipient over IPv6, but the recipient does not accept email messages over IPv6.
5.7.511 Access denied, banned sender
Office 365: The account you are attempting to send from has been banned.
5.7.512 Access denied, message must be RFC 5322 section 3.6.2 compliant
Office 365: Message was sent without a valid "From" email address.
5.7.513 Service unavailable, Client host blocked by $recipientDomain using Customer Block list
Office 365: The recipient domain has added your sending IP address to its custom block list.
5.7.606-649 Access denied, banned sending IP [IP1.IP2.IP3.IP4]
Office 365: The IP that you are attempting to send from has been banned.
5.7.700-749 5.7.705 Access denied, tenant has exceeded threshold, 5.7.708 traffic not accepted from this IP
Office 365: The majority of traffic from this tenant has been detected as suspicious and has resulted in a ban on sending ability for the tenant.
5.7.750 Service unavailable, Client blocked from sending from unregistered domains
Office 365: A suspicious amount of messages from unprovisioned domains is coming from this tenant.
n/a The message can't be submitted because the sender's submission quota was exceeded
Office 365: The user account has exceeded the recipient rate limit (10,000 recipients per day).
Rackspace
421 G2
Your message was rejected because your mail server is opening too many connections to Rackspace. You should limit the number of open concurrent connections to 10 or less. You should configure your mail server's maximum number of connections so it does not exceed this limit or make sure it is properly closing connections.
450 G1F
Your mail was rejected because the lookup of the Reverse DNS record failed. You either do not have an rDNS record or you have a generic record. Your rDNS record for your IP should have the sending domain. You can check your record with our rDNS Lookup tool.
450 G6
This is a temporary error on the Rackspace system related to being able to verify the recipient. This might turn into a permanent fail and send another bounceback.
450 450
Your message was rejected because a loop was detected. This means that the message was passed on to a system and then passed back to the same system. This likely indicates an issue on the recipient's end. This could turn into a hard bounce later, but you probably do not need to take action yet.
450 G1E
This message indicates that your email was not delivered because there was a problem looking up your DMARC record. This is a temporary error, so the message has not failed yet, but could produce another bounceback message that indicates a permanent failure. You should check your DMARC record with our DMARC Lookup Tool.
550 G8
The recipient email address does not exist on the Rackspace mail system. Check the spelling to see if there is a typo and try sending again.
550 G9
The recipient email address does not exist on the Rackspace mail system. Check the spelling to see if there is a typo and try sending again.
550 G3
Rackspace has blocked this message because a virus was detected.
550 G4
Rackspace has blocked this message because a virus was detected.
550 G5
Rackspace has blocked this message because a virus was detected.
550 G15
Your email was rejected because the DMARC record you have in place does not have the sending mail system as a valid sender for your domain. You should check your record with our DMARC Lookup Tool.
550 G18
Rackspace has rejected your message because a virus signature was found in the email.
550 G19
This message was rejected because it is a Multi-part MIME message, which is not allowed by the Rackspace mail system.
550 G1A
Your message was rejected because it contains a banned file attachment. Include an approved file type and resend.
550 G1B
Your message was rejected because it has a banned file attachment. File types related to Windows vulnerabilities are not allowed.
550 G1C
Your message was rejected because it contains a banned file attachment. File types related to exploits in the Winzip program are not allowed.
550 G1D
Your message was rejected because it has a banned file attachment. It includes the CLSID file extension, which is considered dangerous.
550 G7
The recipient's mail system could not verify the address. Check the address for spelling and accuracy. If this email is part of a mailing list, you might want to remove it to protect your reputation.
550 GE
Rackspace is refusing mail for this address. This likely means the address is being used for malicious purposes.
550 GC
This message was rejected because the sender is not allowed to send mail to the Rackspace system due to being blocklisted.
550 G12
This message was rejected because the sender is not allowed to send mail to the Rackspace system due to being blocklisted.
550 G14
This message was blocked because the MX record for the sending domain belongs to a blocked email provider.
Verizon Media
421 Verizon
Verizon Media delayed your message (and may ultimately reject it). They give several reasons as the cause: - Unusual traffic patterns from your sending server's IP address - The message you attempted to send included characteristics of spam - Emails from your mail server have been generating complaints from Verizon Media users - The Verizon Media mail servers are busy when attempting a connection - Other suspicious behavior, which leads Verizon Media to enforce a dynamic deprioritization for your sender's server
421 vzn
Verizon Media delayed your message (and may ultimately reject it). They give several reasons as the cause: - Unusual traffic patterns from your sending server's IP address - The message you attempted to send included characteristics of spam - Emails from your mail server have been generating complaints from Verizon Media users - The Verizon Media mail servers are busy when attempting a connection - Other suspicious behavior, which leads Verizon Media to enforce a dynamic deprioritization for your sender's server
451 Verizon
Verizon Media delayed your message (and may ultimately reject it). They give several reasons as the cause: - Unusual traffic patterns from your sending server's IP address - The message you attempted to send included characteristics of spam - Emails from your mail server have been generating complaints from Verizon Media users - The Verizon Media mail servers are busy when attempting a connection - Other suspicious behavior, which leads Verizon Media to enforce a dynamic deprioritization for your sender's server
451 vzn
Verizon Media delayed your message (and may ultimately reject it). They give several reasons as the cause: - Unusual traffic patterns from your sending server's IP address - The message you attempted to send included characteristics of spam - Emails from your mail server have been generating complaints from Verizon Media users - The Verizon Media mail servers are busy when attempting a connection - Other suspicious behavior, which leads Verizon Media to enforce a dynamic deprioritization for your sender's server
553 Verizon
Verizon Media rejected your message. They give several possible reasons: - Spamhaus has your domain or IP address listed on a blocklist - You are trying to send a message to an invalid email address - Your message failed authentication checks against your sending domain's DMARC or DKIM policy - The message contains characteristics that Verizon Media will not accept for policy reasons - Other suspicious behavior, which leads Verizon Media to issue a permanent rejection for your SMTP connection
553 vzn
Verizon Media rejected your message. They give several possible reasons: - Spamhaus has your domain or IP address listed on a blocklist - You are trying to send a message to an invalid email address - Your message failed authentication checks against your sending domain's DMARC or DKIM policy - The message contains characteristics that Verizon Media will not accept for policy reasons - Other suspicious behavior, which leads Verizon Media to issue a permanent rejection for your SMTP connection
554 Verizon
Verizon Media rejected your message. They give several possible reasons: - Spamhaus has your domain or IP address listed on a blocklist - You are trying to send a message to an invalid email address - Your message failed authentication checks against your sending domain's DMARC or DKIM policy - The message contains characteristics that Verizon Media will not accept for policy reasons - Other suspicious behavior, which leads Verizon Media to issue a permanent rejection for your SMTP connection
554 vzn
Verizon Media rejected your message. They give several possible reasons: - Spamhaus has your domain or IP address listed on a blocklist - You are trying to send a message to an invalid email address - Your message failed authentication checks against your sending domain's DMARC or DKIM policy - The message contains characteristics that Verizon Media will not accept for policy reasons - Other suspicious behavior, which leads Verizon Media to issue a permanent rejection for your SMTP connection
553 USER COMPLAINT
This error means that Verizon users have reported your messages as spam. This is a tricky error to navigate because users can report messages as spam for any reason and often do not understand the effect that button has. You should ensure that any mailing list you are sending to is an "opt-in" list and that unsubscribing is easy. If you use a 3rd-party for sending email, it might not be your fault and other domains sending from the server are causing the problem. If it is your server, you will want to follow best practices to improve your delivery as much as possible.
554 USER COMPLAINT
This error means that Verizon users have reported your messages as spam. This is a tricky error to navigate because users can report messages as spam for any reason and often do not understand the effect that button has. You should ensure that any mailing list you are sending to is an "opt-in" list and that unsubscribing is easy. If you use a 3rd-party for sending email, it might not be your fault and other domains sending from the server are causing the problem. If it is your server, you will want to follow best practices to improve your delivery as much as possible.
553 UNSOLICITED MESSAGE
Verizon has rejected this message because the sending IP has sent too many messages. If this is a new IP, you should "warm-up" the IP by sending a small number of messages and increasing it slowly. Check any address(es) you are emailing to ensure that they are users who have opted-in to receive emails.
554 UNSOLICITED MESSAGE
Verizon has rejected this message because the sending IP has sent too many messages. If this is a new IP, you should "warm-up" the IP by sending a small number of messages and increasing it slowly. Check any address(es) you are emailing to ensure that they are users who have opted-in to receive emails.
553 UNKNOWN RECIPIENT
Your mail server has sent messages to invalid recipients on the Verizon Media email system. This likely means a mailing list that is not up-to-date and has not removed bad addresses. You might also be an open proxy being used to send spam. You can use our SMTP tool to check for an open proxy.
554 UNKNOWN RECIPIENT
Your mail server has sent messages to invalid recipients on the Verizon Media email system. This likely means a mailing list that is not up-to-date and has not removed bad addresses. You might also be an open proxy being used to send spam. You can use our SMTP tool to check for an open proxy.
553 AUTHENTICATION FAILURE
Verizon Media has rejected your message because either it or other messages from your mail sever failed a DKIM check. Verizon says they will reject the message because of the following: - The signing domain publishes a policy which states that all emails from the domain must be signed and authenticated with DKIM to prevent forgery - The signing domain is identified in the "d=" tag of the DKIM signature - The rejected email could not be authenticated against the sending domain's policy, for example, due to a missing or bad signature If you have the headers (sometimes included in the bounceback), you can use our Header Analyzer tool for more information. If you are a listserv, then you want to make sure that the mailing list's address in the "From" and the "Reply-To" fields is the actual sender's address.
554 AUTHENTICATION FAILURE
Verizon Media has rejected your message because either it or other messages from your mail sever failed a DKIM check. Verizon says they will reject the message because of the following: - The signing domain publishes a policy which states that all emails from the domain must be signed and authenticated with DKIM to prevent forgery - The signing domain is identified in the "d=" tag of the DKIM signature - The rejected email could not be authenticated against the sending domain's policy, for example, due to a missing or bad signature If you have the headers (sometimes included in the bounceback), you can use our Header Analyzer tool for more information. If you are a listserv, then you want to make sure that the mailing list's address in the "From" and the "Reply-To" fields is the actual sender's address.
553 CONTENT
Verizon Media has rejected the message due to content such as viruses, phishing attempts, ransomware, other malicious software, or links that have any of the above. Check that your mail server is not an open relay allowing spammers to send through your system with our SMTP tool.
554 CONTENT
Verizon Media has rejected the message due to content such as viruses, phishing attempts, ransomware, other malicious software, or links that have any of the above. Check that your mail server is not an open relay allowing spammers to send through your system with our SMTP tool.
553 RECIPIENT DOES NOT EXIST
The user does not exist on the Verizon Media system. You should not send to this address again to protect your mail server's reputation.
554 RECIPIENT DOES NOT EXIST
The user does not exist on the Verizon Media system. You should not send to this address again to protect your mail server's reputation.
MESSAGE TEMPORARILY DEFERRED Verizon
The Verizon Media mail system has temporarily delayed your message. This is due to your mail server's sending reputation and could also mean that Verizon has recognized mail that violates its guidelines. This message might ultimately end up rejected with another bounceback error.
MESSAGE TEMPORARILY DEFERRED vzn
The Verizon Media mail system has temporarily delayed your message. This is due to your mail server's sending reputation and could also mean that Verizon has recognized mail that violates its guidelines. This message might ultimately end up rejected with another bounceback error.
RESOURCES TEMPORARILY UNAVAILABLE Verizon
This error indicates a problem with the Verizon Media email system. You should try to send the message again later.
RESOURCES TEMPORARILY UNAVAILABLE vzn
This error indicates a problem with the Verizon Media email system. You should try to send the message again later.
421 Yahoo
Verizon Media delayed your message (and may ultimately reject it). They give several reasons as the cause: - Unusual traffic patterns from your sending server's IP address - The message you attempted to send included characteristics of spam - Emails from your mail server have been generating complaints from Verizon Media users - The Verizon Media mail servers are busy when attempting a connection - Other suspicious behavior, which leads Verizon Media to enforce a dynamic deprioritization for your sender's server
451 Yahoo
Verizon Media delayed your message (and may ultimately reject it). They give several reasons as the cause: - Unusual traffic patterns from your sending server's IP address - The message you attempted to send included characteristics of spam - Emails from your mail server have been generating complaints from Verizon Media users - The Verizon Media mail servers are busy when attempting a connection - Other suspicious behavior, which leads Verizon Media to enforce a dynamic deprioritization for your sender's server
553 Yahoo
Verizon Media rejected your message. They give several possible reasons: - Spamhaus has your domain or IP address listed on a blocklist - You are trying to send a message to an invalid email address - Your message failed authentication checks against your sending domain's DMARC or DKIM policy - The message contains characteristics that Verizon Media will not accept for policy reasons - Other suspicious behavior, which leads Verizon Media to issue a permanent rejection for your SMTP connection
554 Yahoo
Verizon Media rejected your message. They give several possible reasons: - Spamhaus has your domain or IP address listed on a blocklist - You are trying to send a message to an invalid email address - Your message failed authentication checks against your sending domain's DMARC or DKIM policy - The message contains characteristics that Verizon Media will not accept for policy reasons - Other suspicious behavior, which leads Verizon Media to issue a permanent rejection for your SMTP connection
MESSAGE TEMPORARILY DEFERRED Yahoo
The Verizon Media mail system has temporarily delayed your message. This is due to your mail server's sending reputation and could also mean that Verizon has recognized mail that violates its guidelines. This message might ultimately end up rejected with another bounceback error.
RESOURCES TEMPORARILY UNAVAILABLE Yahoo
This error indicates a problem with the Verizon Media email system. You should try to send the message again later.
Zoho
530 Must issue a STARTTLS command first
Zoho: Trying to connect SMTP server in insecure mode.
535 Authentication failed
Zoho: Invalid Sendmail token/username.
552 Relaying disallowed as emailaddress
Zoho: Sending email from invalid address domain.
553 5.7.1 virus Win. Test. EICAR_HDB-1 detected by Zoho Mail
Zoho: Virus detected in eml file.
No error code 5.2.1 Subject is mandatory
Zoho: Subject field missing.
No error code 5.2.0 Email size exceeded the policy
Zoho: Attachment size has exceeded the user policy.
burritos@banana-pancakes.com braunstrowman@banana-pancakes.com finnbalor@banana-pancakes.com ricflair@banana-pancakes.com randysavage@banana-pancakes.com