We were able to connect to your mail server on port 25, but the diagnostic session took longer than expected. This could indicate that your email server is under heavy load.
Here are the levels for which we issue warnings and alerts:
Over 5 Seconds: Warning
Over 8 Seconds: Alert
Having this warning on your lookup does not necessarily mean that you will have a problem receiving mail. It is simply a warning that things are less than optimal. This could end up causing users to experience delays with inbound mail.
It is also possible your server is “Tar pitting.” Tar pitting is a technique used by some email servers to slow down spammers. The idea is that legitimate senders will wait longer to establish a connection than spammers will.
Here is a link to a link to the TechNet article with more information about Tarpitting
Are you managing your email delivery?
Email delivery is more than running an email server, or regularly checking for blacklists. To really ensure you customers get your email, you need to setup SPF, DKIM and DMARC. If you aren't manage your DMARC configuration and responses from email providers, you don't know if your customers are getting your email.
MxToolbox is YOUR expert on email deliverability. MxDelivery Center can help you setup and analyze your DMARC, DKIM and SPF to give you the insight you need to make email configuration changes and get your emails to your customer's.