List hygiene
Keeping a mailing list to people who asked for mail and still read it: removing bounces, complainants, unsubscribes and long-inactive addresses.
What it means
Providers state the basics. Apple asks bulk senders to have a policy for bouncing addresses, remove inactive subscribers periodically and never reactivate addresses on an unsubscribe or suppression list. Yahoo says to monitor hard and soft bounces and inactive recipients. Microsoft's high-volume sender recommendations include removing invalid addresses regularly.
M3AAWG suggests removing an address that bounces at least twice in a row over two weeks or more, and Spamhaus suggests removing addresses after three sequential bounces or sequential bounces over more than two weeks. Both stress acting on unsubscribes and feedback-loop complaints at once.
No amount of cleaning turns a purchased or scraped list into a permission-based one.
Related terms
On this site
Sources
What this definition rests on. The wording is ours; the facts are theirs.
- Apple Support: Postmaster information for iCloud Mailsupport.apple.com
- Yahoo Sender Hub: Sender requirements and recommendationssenders.yahooinc.com
- Microsoft Tech Community: Outlook's requirements for high-volume senderstechcommunity.microsoft.com
- M3AAWG Sender Best Common Practices, version 4.0 (August 2026)m3aawg.org
- Spamhaus FAQ: Marketing emailspamhaus.org
All 432 terms in the glossaryThe wiki: blocklists and bounce codes