List hygiene
Why it matters
Mailbox providers judge a sender by how recipients and servers react. Hard bounces and spam complaints damage domain reputation, and a damaged reputation sends even good emails to spam. Gmail and Yahoo have published a ceiling for bulk senders: spam complaints must stay under 0.3 percent of messages, with Google advising to stay under 0.1 percent. Old addresses can also become spam traps, which are addresses that mailbox providers keep to catch senders who do not clean their lists. List hygiene also saves money, because most email tools charge by list size.
How to apply it
- Remove hard bounces automatically after every send. These are addresses that permanently do not exist.
- Watch soft bounces, such as a full mailbox, and remove an address after several in a row.
- Set a disengagement rule, for example no clicks in six months, and send a last re-permission email before suppressing the contact.
- Judge engagement on clicks as well as opens, because some mail apps load images automatically and inflate open rates.
- Verify addresses before a large send, especially on a list that has been idle for a year.
- Check deliverability after each clean-up to see the effect.
What it is
An email list decays. People change jobs, companies close, addresses are mistyped, and subscribers stop reading. List hygiene is the regular clean-up that deals with it. It removes addresses that bounce, merges duplicates, fixes typos such as "gmial.com", and deals with contacts who have not opened or clicked in months.
It is a routine, not a one-off project. A business list can lose a noticeable share of its addresses to job changes every year, so the clean-up needs a schedule, for example after every send for bounces and quarterly for inactive contacts.
It differs from data hygiene, which covers all customer data. List hygiene is the email-specific part, and its aim is that every address you send to is real, reachable and wants the message.
Common mistakes
Buying lists, which brings in spam traps and people who never agreed to hear from you. Never removing anyone, so that the list looks big and performs badly. Deleting unsubscribes instead of keeping them on a suppression list, which risks mailing the same person again.
