Managing Email Delivery: Keeping your Verified Sender List updated


Did your Accounting department add a new billing vendor? Marketing department decide to try a new email marketing solution?

Time and time again, these situations often lead to email delivery problems that go unnoticed until after you learn that no one has been receiving your email for some time. In many cases, those making these changes are unaware of the importance of maintaining and updating their business's email focused DNS records, let alone understanding what DNS records are. Now, imagine those two examples repeated over and over again as new vendors come and go or business infrastructure changes. The result? Unknown email delivery problems that will cost time and money.

SPF Records and Forgetting to Add New Senders to Your Approved Sender List (SPF Record)

If your business sends email, you already have an SPF Record set up. If you don't have SPF for your domain and you're sending email, you'll need to get a record set up ASAP! If your business utilizes third parties to send email, at some point the day will come when you'll need to update this list. Keeping SPF updated and correct across all outbound domains that send email is an important task that needs attention. If the SPF Record is missing a sender or is misconfigured, a receiving mail server or cloud-based email service (e.g., G Suite, Microsoft Office 365) might block the message from being delivered.

One of the most challenging aspects of email is managing this ever-expanding list of senders that are used across multiple departments and/or vendors of your business. This has a real work impact as most businesses only realize too late that their SPF record needs to be constantly updated with each vendor or internal service they add over time. Until customers start asking where your emails are or your email revenue drops, you probably won't even think to ask questions, such as: Did our administrators start using a third-party email provider without telling us? Is the Sales team still using that lead software, or did they switch to Salesforce? Better yet, probably nobody will ask... Has anyone updated the SPF record to be current?

Basically, the “too many cooks in the kitchen” expression applies to this situation. This is where having an email partner like MxToolbox makes a lot of sense. Taking MxToolbox's years of email expertise and Delivery Center service, your team will immediately know when these types of problems occur, long before you notice the revenue drop or customers start calling in.

Too Many Senders?

In today's world of email, most businesses send email through a number of vendors (think Office 365, MailChimp, Salesforce, etc.), along with their own systems. After a certain point, having too many senders becomes a major problem. To put it bluntly, email servers will reject your mail, every single piece of it. Known to email admins, the 10 lookup rule with SPF records has become a real problem for businesses that use multiple email services.

Use Office365? That will be three (3) lookups. Send marketing email with SendGrid? That's another one (1). Send trouble tickets via Zendesk or website status updates through There's another two (2). We're already at six (6) lookups and that's only using a small subset of vendors. With all of these vendors, now that limit of 10 doesn't seem difficult to reach.

The really scary part is that nearly all businesses are unaware that there's a limit and when they exceed it. This lets good mail get rejected, losing your business valuable revenue from your email program. To prevent situations like this from happening, MxToolbox monitors your senders as part of the Delivery Center service. Add too many vendors? We'll instantly alert you.

Sending from Subdomains, too?

Often overlooked when sending email is the importance of unique SPF records for every subdomain that sends email. Do your marketing campaigns come from Then you need a unique SPF record.

For example, a business sends email via two (2) domains: and To ensure that email will be delivered, both of the two subdomains need to have their own SPF record. Failing to add an SPF record for one of the domains will lead to delivery problems. This requirement continues in the event the business decides to send email from other domains, such as the company's Marketing department decides to start sending marketing promotions via

This problem with subdomains often occurs from how easy it is to spin up a subdomain for a unique campaign or maybe a department function. Do your customers get invoices from For this reason, many businesses hit this pitfall with SPF and only later learn about the problem, after revenue has been lost in the process. With those three (3) examples plus your business's primary domain, that's four (4) domains that need unique SPF records.

Keeping an eye on all of the above scenarios can seem a daunting task, along with ensuring consistent communication that keeps all parts of your business on the same page about these vendors/sender problems. This is where a partner like MxToolbox comes in to offer our years of email expertise and Delivery Center software to make sure your business is alerted to these kinds of situations long before they become email crippling problems.

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