The 2025 Deliverability Checklist


Back a few months ago, we warned all you email marketing senders to hold off on making any significant changes to your sending infrastructure and marketing strategy, so as not to upset the apple cart in a way that would cause you deliverability problems during that most important time of the year for email marketing revenue – Black Friday, Cyber Monday, Giving Tuesday, and most of December.

Now that the holidays are behind us, it's time to circle back around and take stock of what you're doing. Look to see if there are things that you don't have configured correctly, see where you can better set yourself up for future deliverability success, and look for opportunities to improve your email marketing strategy.

Here are the most important things I'd suggest reviewing this month.

Look for inbox placement issues that you may not have had time to check for previously. If you're able to break down opens and clicks by domain, check the top 4-5 and see if opens or clicks are much, much lower than at other domains. Caveats abound here; open tracking is imperfect nowadays (but still directionally useful) and some domains do seem to always have lower or higher open rates than other, but I'm talking about a 3% open rate for Yahoo Mail versus a 40% open rate for Gmail. Or vice versa. In a situation like this, you've probably got a spam folder issue at the domain with the much lower open rate.

Running on a dedicated IP address email marketing platform? Review your number of sending IP addresses versus min/max daily and monthly volume. If you send more than two million email messages per day, I recommend having one IP address for every two million per day. Sending six million email messages per day? That'd call for three dedicated sending IP addresses. Maybe even go a bit more conservative for that, to account for future growth. Add an extra IP address, and let the volume grow over time, just being careful to try to keep it under two million email messages per day.

A dedicated outbound mail server (MTA) can certainly send more than two million messages per day; but more than that from a single IP and there's a good chance you'll see some sort of delays attempting to send to various big mailbox providers. And you want a given campaign to be delivered in a few hours at most, not 18-24 hours.

Be careful not to utilize too many sending IP addresses. A sending IP address really ought to send at least a couple hundred thousand email messages per month. Much less than that, and mailbox providers likely will not see enough volume from that IP address to generate a solid reputational view over time; leaving you in inbox limbo. You'll have an unknown reputation, which is nearly as sub-par as having a bad reputation. You don't want that.

One size does not fit all; I've certainly seen B2B senders do just find with lower volumes on a dedicated sending IP address. And various platforms offer differing advice for IP strategy – possibly with good results. (I tend to think that published strategy on this front usually doesn't come from idiots, even if it differs from my typical guidance.) But I do still think this guidance is a good starting point.

Review your domain segmentation strategy. Got enough volume to separate transactional and marketing streams into separate subdomains? Now's a good time to move forward on that. "Enough" volume can be hand-wavy, but generally speaking, you can support a domain reputation with just a few thousand email messages a month. Separate subdomains for separate mail streams helps segregate domain reputation, to prevent issues with marketing best practices from negatively impacting deliverability for transactional (or 1:1 corporate) email messages.

Review technical settings to make sure everything is configured correctly. Maybe even consider changing email marketing automation platforms, if you can find a platform that better suits your needs. Do you have DKIM properly configured? And I mean: DKIM signing for YOUR domain, not just the platform's default domain. This is so important to stand out as you when sending to mailbox providers, instead of just appearing like random customer #33 of a given email marketing or newsletter platform. What other technical settings are there for your platform?

Don't forget to warm. If you're configuring new IP addresses, new sending domains (including subdomains), or new platforms, don't forget to introduce them to the world slowly through IP warming or domain warming.

Implement DMARC (properly), and consider BIMI. Domain-based Message Authentication, Reporting and Conformance (DMARC) is pretty much a necessity nowadays thanks to the updated Yahoo and Google sender requirements. But if you implement the bare minimum, with no reporting and a DMARC policy of p=none, you're not protecting your email domain against phishing and spoofing. It's time to move up to p=quarantine or p=reject. And once you've done that, you can implement a Brand Indicators for Message Identification (BIMI) sender logo to stand out in the inbox.

Sign up for Google's Postmaster Tools reputation dashboard, if you haven't already. Now's a great time to register your sending domains so that you can monitor your domain reputation more closely.

Implement that subscriber lifecycle management (and sunsetting) policy. Suppressing inactive subscribers after a time helps to improve inbox placement by boosting engagement; it does you no good to keep mailing uninterested subscribers forever. Send them a winback campaign (or two) and then drop them from your regular campaigns, so as not to drag down your engagement and land your campaigns in the spam folder (especially at Gmail).

Review your overall email marketing and engagement strategy. Those drip campaigns you didn't set up before because you didn't have time – how about now? What about a welcome message, thank you message, and ensuring that your signup process is clear and easy to find, with a link or form on every page on your website. Grow your list and drive engagement with the right kind of additional email touchpoints.

And finally, run a test to make sure your email headers and message settings are fully correct, set up to maximize deliverability success as much as possible. A tool like Aboutmy.Email is perfect for that.
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