The Importance of Email List Hygiene

You’d be forgiven for believing that the size of your email list carries more weight than the quality of the email addresses it contains. Truth is, sending campaigns to inactive or worse still; invalid email addresses can cause nightmarish problems for your online-and-sender reputation. A dirty list sends a message to the ISP’s that you don’t really know about your customers or about following industry standards. Now more than ever, thorough email list hygiene is a vital good habit that any email marketer needs to adopt if they want to stay ahead of the game, and certainly the ISP’s.

It might seem like a hassle to scrub up your list, but here are 5 quick and easy ways to keep your list shiny and clean. (Remember the more often you do it, the more effective it is).

Honouring unsubscribes

If someone goes through the process of unsubscribing then honour it and remove them as soon as possible from your mailing list. Forget all the nonsense about having a certain amount of time to do this, it’s not complicated and it’s better for both you and the subscriber at the end of the day. You won’t be wasting your money sending emails to people who aren’t interested and they get to bow out gracefully, hopefully before they get really irritated and report you for spam.

Address bounces as soon as possible

Any bounces (hard and soft) need to be addressed immediately. If it’s a hard bounce it’s likely that the email address is invalid or non-existent in which case you can easily get it verified. It’s a simple process and sites such as and offer free email verification.

The format of the email is tested as well as the validity of the domain and user. It’s important that you keep an eye on soft bounces too, anything that hasn’t been opened by a subscriber in 6 months or more needs to be removed (not deleted) from your list. Keep all inactive email addresses together so that you can approach them at a later stage with a specially targeted reactivation campaign. You can read more about re-engaging with your inactive subscribers here.

Clean up your emails

If your email list is small enough, you can manually go through it and check for simple data entry mistakes such as misspelt domains ( and for example). Once they’ve been corrected then make a point of running them through the email verification tool again. If they come back with an error after this then discard them.

Consider data validation software for your forms

Make use of data validation on your subscription forms. By validating each field you can ensure that any information entered is formatted correctly before it is accepted into your list. It also ensures visitors correct their mistakes immediately, which saves you the trouble of having to do this later.

Configure suppression lists

Often you’ll find distribution accounts, such as “sales” or “all” on your email list, especially if it’s a bought or rented list. It’s good practice to remove any that you find and this can easily be done by including common email addresses such as “all” and “sale” to your suppression list. It’s important to note that ISP’s often target invalid and non-existent email addresses in these accounts for spam traps (honey pots). Once they’ve tracked you they’ll place a temporary (if you are lucky) or permanent (if you are not so lucky) block on any messages to that email. A temporary block is normally lifted once the offending address is removed from the list, so the sooner you do this the better.


Set a regular list cleaning schedule

Make a point of regularly sifting through your email list every 6 months or so (depending on how fast it grows), you can rest assured that it’ll remain clear of any spam-trap luring email addresses, and of course you’ll also save yourself quite a bit of money (and trouble!) in the long run.


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