September 26, 2018

Deliverability 101: What is List Hygiene?

It’s time you take care of your email as well as you take care of yourself. Your email lists deserve good hygiene, too! List hygiene is a process of data validation undertaken by email marketing teams to ensure that they have a clean list of people to whom they send their campaigns. Savvy email professionals will tell you without hesitation that good delivery rates are closely tied to having good data. Removing the crud that builds up over time from your eligible sending pool will provide you with a clean list that will give you a greater return on your email investment.

What is a clean list?

It’s simple: It’s a list full of recipients actively engaged with your email deployments within the last six months (at max) and lacking in nonresponders.

What are the consequences for skipping this all together?

This one’s even simpler: Mailbox providers (MBPs) and blacklists will make sure much or all of your mail does not reach its intended recipient. Your reputation is based on your sending practices, and continuous sending to older, unengaged recipients is your sure-fire way to tank it.

What should be in a list?

The key metric to have in mind when you are starting down the path of removing potentially harmful data from your list is six months. Yes, it’s so important we already touched on it earlier! This should be your cut-off for engagement with any particular address to which you have been actively sending. After that point, they either don’t want your stuff any longer and haven’t gotten around to unsubbing yet, or that email address is not owned by an actual person anymore and is now being recycled into a trap. Segment non-responders off your list, creating a new list of folks to try to re-engage; however, you should totally remove those far outside of the six-month window. Get a sunset policy into place!

After you have taken care of that chunk of data, you can start to pick off other addresses which shouldn’t have been added into your data pool in the first place:

Role addresses:
The intention of a role account is to be a specific task-oriented email address and, most importantly, is not a singular person. These are almost always monitored by a large group with their own individual addresses. It would be something like “support@” or “info@” account. These typically do not intentionally sign up for email lists and are not worth the risk to your sending health to continue firing promotional or marketing mail to these endpoints. Comb through your database for anything starting with things like abuse@, postmaster@, info@, support@, and so on.

Typo Domains:
A typo domain is a domain that is a close approximation of a real mailbox provider (e.g. or These addresses often point to spam trap networks and will get you in hot water if you continue sending to them for an extended period of time. Have a look into your mailing list for addresses like this and compare them to their engagement rates. If you are sending to typos with absolutely no clicks or opens, you can rest easy knowing they can be safely removed.

How do you proactively avoid a dirty list?

Starting at the point of acquisition, there are several things you can implement to verify the addresses you are adding into your database. Whether you are adding addresses through a web form or copying them manually from a sign-up sheet, you are never going to 100% ensure it’s a valid address the first time, so using a double opt-in will be your best tool in fighting against dirtying your list. By sending a welcome email requiring the recipient to confirm their subscription, you are verifying the recipient’s identity and getting some engagement metrics (which MBPs love to see!). This may seem like a cumbersome step on the surface, but by initiating this one extra touch you are putting yourself in the best position for continued engagement.

List hygiene is a must and will only prove to positively benefit your overall email health in the future. By making some minor adjustments, you will be able to target the right audience that will help grow your brand.

Author: Alexander Heinz

Alex is a Solutions Architect at 250ok with nearly a decade of experience in the industry (Adobe Campaign and Vistaprint). All of his time spent in the email world has been in roles focused on solving deliverability issues and developing tools and strategies to optimize clients inbox performance.

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