List hygiene
The practice of keeping an email list clean — removing bounces, suppressing unengaged subscribers, validating addresses.
List hygiene is the ongoing practice of keeping an email list clean: removing hard-bounced addresses, suppressing chronically unengaged subscribers, validating addresses before sends, and using opt-in patterns that prevent low-quality additions in the first place.
The core hygiene operations are bounce processing (suppress on first hard bounce), engagement-based suppression (remove subscribers who haven't opened or clicked in 90–180 days), list validation (use a service to verify addresses before sends, especially after a list-acquisition event), and regular permission passes (re-confirming consent every 6–12 months for dormant segments).
The counterintuitive truth of list hygiene: smaller lists outperform larger lists on virtually every metric. A 10,000-subscriber list with 30% engagement will out-deliver, out-convert, and out-revenue a 50,000-subscriber list with 6% engagement. List size is a vanity metric; engaged list size is the real number.