List Hygiene

List hygiene is the ongoing maintenance of an email list: removing addresses that bounce, suppressing people who unsubscribed or complained, and managing subscribers who have stopped engaging.

Why it matters

Mailbox providers judge you on how recipients treat your mail. A list full of dead or unwilling recipients produces hard bounces, complaints and spam trap hits, which hurt sender reputation for everyone on the list, including those who want your mail. Good hygiene also saves money where pricing depends on list size and makes engagement metrics more meaningful.

Example

A simple monthly routine:

1. Remove every address that hard bounced (a 5.1.1 unknown-user error).
2. Suppress anyone who unsubscribed or complained, permanently.
3. Move subscribers with no opens or clicks in, say, 12 months to a re-engagement series, then remove those who still do not respond.
4. Validate new signups with double opt-in.

Common mistakes

• Re-importing an old export that contains previously unsubscribed addresses.
• Deleting suppression records, so those people are mailed again.
• Judging inactivity only by opens; open tracking is unreliable (see tracking pixel).

Related

• Sender Reputation
• Spam Trap
• Double Opt-In
• Email Bounce
• Tool: Email deliverability test

This page is general information written by our editorial team and updated when documentation changes. Servers and providers differ, so test changes safely first. See our editorial policy and disclaimer.