List hygiene for better deliverability

Article author
Kelly Sutter
  • Updated

List hygiene is at the core of every successful email program. It is the practice of keeping your subscriber lists free of old or invalid emails. Sending to disengaged emails and spam traps leads to blocklisting, abuse complaints, high bounce rates, and low inbox deliverability. Good list hygiene leads to the best deliverability and high engagement stats. Keep list hygiene front of mind and practice to successfully reach your subscribers.


Step 1 // Collect real addresses

Collecting real, double-opted-in subscriber addresses is critical. Beware of quick list growth methods like purchased lists. There is no such thing as a targeted or opted-in purchased list. Subscribers must be given the opportunity to opt in to your email program.

Best practices for signup


Step 2 // Remove opt-outs and hard bounces

After you’ve done the hard work of acquiring subscribers the right way, the next step is managing subscriber’s sending status. Make it easy for them to unsubscribe or update their preferences. Subscribers who opt out or submit abuse complaints should be removed from your list immediately. This is the law in both the US and internationally. Addresses that hard bounce are always invalid and all ISP postmaster guidelines ask senders to remove these addresses immediately. Resist the urge to resend to hard bounce addresses for any reason. Consider the opt-out and hard bounce as the end of the relationship with the subscriber.

Best practices for unsubscribing


Step 3 // Remove disengaged subscribers

Over time even a good address can change to a bad one. Subscribers change mailbox providers and their inbox becomes dormant. ISPs convert abandoned mailboxes to their own spam traps, or the addresses become part of mainstream blocklists like Spamhaus. Mailing to spam traps is the primary reason senders end up on blocklists.

Sending to opted-in and actively engaged subscribers is the only way to avoid spam traps. Subscribers with no activity (opens and clicks) for six months should be removed from your lists. We know, saying goodbye can be so hard. Try running a reengagement campaign to see if any subscribers still want to receive emails. Subscribers who don’t respond to reengagement emails should be removed from your mailing lists.

How to increase email campaign engagement
Suppressing disengaged subscribers