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Allow-Listing for Email Communications: Tips for Email Marketers

Want to get your emails past spam filtering? Being on the allow-list can help you ensure your emails are delivered. Learn more!

Now more than ever, email marketers are finding it difficult to get messages through multiple levels of spam filtering at private domains. The large ISP and “freemail” providers are also becoming stricter as the threat landscape evolves. In some cases, especially with private domains, mail will not be accepted unless (at minimum) the sending IP(s) and domain are added to their internal allow-list.

Let’s look at some tips for getting your emails past those bouncers and onto the guest list.

With that said, keep in mind that even if your domain and IP(s) are on an allow-list, it does not guarantee that your mail will get delivered. The most important aspect of email deliverability is your overall sender reputation (list practices, sending history, content, volume, engagement, etc.) and being on an allow-list is only a foundational measure.

Before we dive in, let’s look at a couple FAQs.

  1. What is allow-listing?

An allow-list or safe-sender list (previously known as “whitelist”), is an internal list controlled by either the user, mailbox provider or spam filter admin, that contains information about legitimate senders (that they want to receive messages from) to help get them to the inbox. The types of sender information you may see added to these internal lists are the IP addresses of the sending mail server(s), the sender’s “from” email address, sending domain, and/or the sender’s bounce/envelope domain.

  1. What are some reasons you’d reach out to your contacts to allow-list?
  • Prior to transitioning to a new sending platform.
    • Before moving to a new email provider, you would want to alert your current subscribers to notify their IT professional about the change to make sure there are no interruptions to their email communications from you. This would be the time to provide the new sender information (sending IPs, domain, etc) to your contact list.
  • When troubleshooting a deliverability issue.
    • One method to resolve (or at least see if it might be the cause) is to check if the sender’s IPs (your IP) and domains have been added to the recipient’s allow-list.

So, how do senders get their email communications onto an allow-list?

4 Ways That IP Addresses Can Be Allow-Listed for a Sender

1. Sign-Up Forms

The best place to start when it comes to allow-listing is right at the beginning: your subscription method. When someone signs up to receive emails from your organization (think: website, membership forms, etc.) it’s best practice to let them know the email address and IP address(es) that are being used to send your email communications.

You can provide this information in the form of a confirmation page after someone submits their information, or even better yet, in a confirmed opt-in email that is triggered from the sign-up process. The confirmation page or email should contain your visual “from” address, the bounce domain, and the IP address(es) used to send your messages (you can get this info from your email provider).

2. IT at Receiving Organizations

When troubleshooting deliverability issues, the first thing I like to ask is, “Who is reaching out to you letting you know they’re not receiving your message?” Those are the recipients that you want to advocate on your behalf at their organization to get your messages allow-listed. Ask them to reach out to their IT department to allow-list the sending domain, the bounce domain, and all sending IPs used to send your messages.

3. The Postmaster Method

If you are struggling to get mail delivered to a certain domain, it may make sense to reach out to the postmaster on that domain to see if they could do the allow-listing for your recipients. Keep in mind that the preferred method is to have the recipient reach out because many times the postmaster or IT department will not correspond or work directly with a sender. If you do decide to go down this avenue, then you will want to send a message to “postmaster@[domainwithdeliveryissues]” and say the following,

“Hi- We are looking to gather some insight on some deliverability issues we are having when sending from [insert your company name]. We have received the following SMTP bounce response from your mail servers [insert bounce response here or explain the issue]. Is there any additional information that could help us determine the cause of the issue?

We are sending from [insert your “from” domain] with the following IP(s) [insert your sending IPs], so that you have more information on our sending system and if there is potential to add us to your allow-list. Thank you so much for your assistance!”

4. ESP Allow-Listing

There are a few allow-listing providers out there for ESPs (or IP owners for email) which provide a validation method to prove ownership and legitimacy of the IP addresses and domains used in sending emails. This can provide a small amount of protection to the sending IPs/domains for use in email communications. This process is complete by the ESPs and is separate from the individual recipient allow-lists.

Once you’ve given these four tips a shot, your progress toward the allow-list should be in good shape. Make sure you brush up on these other email deliverability best practices.

Amanda DeLuke

Amanda DeLuke, CIPM, is an Information Security Assurance Specialist at Higher Logic and certified in privacy management. Her deliverability expertise turned into a curiosity and passion for all things privacy & security. She is a Program Chair for M3AAWG (Internet Anti-Abuse working group) and a member of the International Association for Privacy Professionals (IAPP). While she’s not busy at work, she is a mom to identical twin boys and a volunteer mentor and cycling coach for young girls.