Maintenance: the recurring habits
Four habits keep an existing list clean, roughly in order of impact.
Remove hard bounces immediately. A hard bounce means the address permanently does not accept mail. Every ESP exposes this; suppress those addresses after one occurrence, because repeat sends to dead mailboxes are the clearest possible signal of a stale list. The difference between bounce types is covered in the email bounce rate guide.
Set a sunset policy. Decide how long a subscriber can ignore you before you stop mailing them, commonly 90 to 180 days without an open or click. Dormant addresses drag engagement metrics down and are where recycled spam traps live: addresses that once belonged to real people and now flag careless senders.
Run re-permission before deleting. One "do you still want these?" campaign to your dormant segment recovers the genuinely interested and gives everyone else a clean exit. Whoever ignores it gets suppressed, not argued with.
Re-validate before big sends. Lists decay even without bounces: mailboxes get abandoned and domains lapse. A bulk validation pass before a high-volume campaign, product launch, or migration to a new ESP catches what accumulated since the last cleaning; the workflow is described in bulk email validation.
What to do this week
If your list has never been cleaned, the sequence is: export and validate the full list, suppress invalid and disposable addresses, segment the rest by last engagement date, send a re-permission campaign to the dormant segment, and only then add real-time validation to your forms so the problem stops rebuilding. A free pass over a small list fits inside Abstract's free tier, and the step-by-step version of the cleanup is in how to clean your email list free. For the managed workflow, see the email list cleaning solution.
Frequently Asked Questions
What does email list hygiene mean?
Email list hygiene means keeping your list limited to valid, deliverable, engaged addresses through two kinds of work: validating new addresses at capture, and routinely removing addresses that bounce, go dormant, or become risky.
How often should I clean my email list?
Suppress hard bounces continuously, review engagement quarterly, and run a full validation pass once or twice a year, plus before any unusually large or important send. High-volume senders clean more often because decay scales with list age and size.
What is email scrubbing?
Email scrubbing is the cleanup half of hygiene: running your existing list through validation and engagement filters to remove invalid, dormant, and risky addresses. Hygiene adds the preventive half, stopping bad addresses at signup.
What bounce rate is considered too high?
Above 2 percent deserves attention and above 5 percent is a list-quality problem. Mailbox providers read sustained high bounce rates as evidence of purchased or stale lists and respond by routing your mail to spam.
Do inactive subscribers really hurt deliverability?
Yes. Mailbox providers weigh engagement when deciding inbox placement, so a large dormant segment lowers the standing of every send. Dormant addresses are also where recycled spam traps appear.
Should I buy an email list to grow faster?
No. Purchased lists arrive full of invalid addresses, spam traps, and people who never consented, which is precisely the combination that gets domains blocklisted. Permission-based growth with validation at capture grows slower and delivers far better.
