Why It Matters
Your list degrades naturally over time. People change jobs (and email addresses), companies go out of business, and mailboxes get abandoned. Industry data suggests email lists decay by about 22% per year. If you're not actively cleaning, nearly a quarter of your list could be dead weight within 12 months. That dead weight costs you money (ESPs charge by subscriber count) and hurts your deliverability.
How It Works
List hygiene combines several practices. Bounce management automatically removes addresses that hard bounce. Engagement-based sunsetting removes subscribers who haven't interacted in a defined period (commonly 90–180 days). Validation tools check addresses for syntax errors, inactive domains, and known spam traps. Suppression lists prevent re-adding addresses that have previously bounced, complained, or unsubscribed. Together, these keep your list lean and healthy.
Quick Tips
- Set up automatic removal of hard bounces — there's no reason to ever retry an address that permanently failed
- Run your full list through a validation service every quarter; it catches addresses that have gone bad since your last send
- Before removing inactive subscribers, send a re-engagement campaign — some will come back, and those who don't confirm they should go