A Guide to Email Marketing List Hygiene

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The most common email delivery and inbox placement problems stem from sender reputation, which is a measure of your trustworthiness as a sender.  Aside from not obtaining explicit permission, the most typical pitfall that can damage your reputation is failing to maintain your marketing list.  Over time, some email addresses on your list will inevitably change hands, be deactivated, or worse, be converted into a spam trap.  Additionally, some recipients may forget they subscribed, thus effectively negating any permission you have obtained.  

When this list degradation occurs, you might see symptoms such as low engagement rates, excessive hard bounces, spam complaints, junk folder placement, or even blacklistings from sending to spam traps.  Unfortunately, the degradation usually occurs slowly, so these symptoms may go unnoticed until it’s too late. Since it can be difficult to repair a damaged sender reputation, cleaning your list by removing recipients that are at risk for degradation is a critical preventative measure.


Identifying Risky Addresses

To maintain the hygiene of your list, these high-risk email addresses should be removed on a regular (e.g. monthly) basis :

  • Role Accounts:  Email addresses that consist of a role instead of a name, like info@, admin@, or sales@. Role accounts are often shared or passed down as people change roles at a company, which means you could be sending marketing to someone without permission.

  • Lost or Forgotten Recipients:  Permission degrades over periods of inactivity. Don’t send to an old list of recipients if you haven’t been emailing them within the past 6 months, even if you obtained explicit permission at the beginning of your relationship.

  • Unengaged Recipients:  As a general rule, these are recipients that have not opened or clicked in the past 6 months.  Set an appropriate threshold for what constitutes unengaged based on how often you send. If you send to your recipients daily, they could be considered unengaged if they don’t have any activity after only one month.  If you send less frequently, like once per year, this reduces the information available to determine if a recipient is engaged. Instead of increasing the risk of damaging your sender reputation by setting a longer time window for which recipients are unengaged, find a way to increase your sending frequency (to at least every 3 months) and use 6 months as your engagement threshold.

Re-engage Early

If you get the feeling that your recipients are actually interested, but they aren’t opening or clicking, you can take action to prevent them from qualifying as unengaged. Confirming opens usually relies on a tracking pixel, so this can be unreliable for email clients that don’t download images by default. To offset this, every email should include some opportunity for you to measure engagement, whether it’s a link to click or an infographic that they’ll want to see.   

For at-risk recipients that are nearing your engagement threshold, use a re-engagement campaign: offer a special promotion or incentive for them to show signs of interest. It’s also appropriate to ask them directly if they are still interested or if their interests have changed. Let them know you won’t be sending more if they don’t give you some indication, like clicking a confirmation link or updating their subscription preferences.  Just don’t wait until they become too much of a risk to send them marketing. Recipients that do not open or click after a re-engagement campaign should ultimately be removed from your email marketing list, though you may still recoup the leads by contacting them via other channels.


Trimming the Fat

Removing high-risk addresses can be painful at first as every marketing lead seems like a potential conversion, but don’t overlook the fact that not all leads have the same potential for conversion.  Recipients that have not engaged with your email for 6 months have a very low potential to convert as compared to those that have recently subscribed, so you’ll want to maximize inbox placement for those with high conversion potential.  Remember that unengaged recipients present not only risk to your sender reputation, they’re also actively hurting it by not engaging. The slight chance of conversion is not worth the cost of failing to deliver email to your hottest leads - your new subscribers and engaged recipients.