How often should you clean a list?
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Email addresses decay at roughly 20-30% per year. People change jobs, abandon inboxes, let domains expire. A list you built two years ago has meaningfully more bad addresses in it today than it did the day you built it, even if you haven't done anything wrong. Cleaning frequency is how you stay ahead of that decay instead of letting it compound.
Frequency by send volume
High-volume senders (100K+ per month): Review hygiene monthly. At this volume, accumulating bad addresses has compounding effects on your sender reputation faster than lower-volume senders. Monthly cleaning or monitoring also means smaller problems are caught while they're still small.
Medium-volume senders (10K-100K per month): Quarterly is the right cadence. Enough time for decay to accumulate meaningfully, frequent enough that you catch problems before they affect deliverability significantly.
Low-volume senders (under 10K per month): Every six months at minimum. Even at low volume, a list that hasn't been cleaned in 18 months will have accumulated enough bad addresses to create bounce and spam trap problems.
Trigger-based cleaning (not just calendar-based)
Calendar-based cleaning is the floor, not the ceiling. You should also clean after any of these events: importing a new list or adding a new list source, buying or merging with another business's contacts, any campaign where bounce rate exceeded 2%, or a period of list inactivity (if you haven't sent in six months or more, clean before the first send back).
What cleaning actually means
A full cleaning pass does several things: removes invalid addresses (syntax errors, dead domains), identifies likely spam traps, flags addresses with no engagement history, and surfaces role addresses (info@, contact@) that are higher risk. Not every flagged address needs to be deleted immediately. Some go to a "monitor" segment for a re-engagement attempt before suppression.
If your list is older than a year and hasn't been cleaned, or if you're seeing rising bounce rates, we handle this (hi ;)). reviewmyemails.com/done-for-you.
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