List Hygiene

List hygiene is the housekeeping side of email marketing: you regularly identify addresses that bounce, never open, never click, or were mistyped at signup, and you stop sending to them. The goal is that the people still receiving your campaigns are people who might actually read them, rather than a number that looks good in a dashboard.

It is not the same as Segmentation, which sorts engaged subscribers into groups for different messages. Hygiene decides who stays on the list at all; segmentation decides what the survivors get. It is also not a Sunset Flow, which is one automated mechanism for doing hygiene rather than the practice itself.

There is no single hygiene score. Most stores watch three things: bounce rate (bounces divided by messages sent), the share of the list that has not opened or clicked in a defined window such as 90 or 180 days, and spam complaints per thousand sends. Calculate engagement against your full subscriber count, not against recent senders only — the full count is the honest denominator, because excluding people you already stopped emailing hides exactly the dead weight you are trying to find.

Deliverability is the outcome hygiene protects; Sender Reputation is the mailbox provider's running judgement that hygiene feeds. A Sunset Flow is the automation that suppresses lapsed contacts for you. Open Rate and Revenue per Recipient both move when you clean a list, because the denominator shrinks — check whether revenue actually rose or only the percentage did.