How to Clean an Email List Before a Campaign
A list that has not been touched in months is not the same list it was when people signed up. Jobs change, inboxes get abandoned, and domains lapse. Cleaning it before you send takes five steps.
1. Export the full, current list
Pull a fresh export from wherever the list actually lives — your ESP, CRM, or e-commerce platform — rather than reusing an old file. Include every subscriber, not just the segment you plan to email first; it is easier to filter a clean list down than to clean a partial one twice.
2. Remove duplicates and obvious junk
Deduplicate by email address (not by name — the same person can sign up twice with slightly different details). While you are in there, strip out internal test addresses, team inboxes that got added during setup, and anything that is obviously not a real subscriber. This is quick, and it shrinks the list before the slower step.
3. Verify what is left
Run the deduplicated list through a verification pass that checks format, domain and MX records, and mailbox existence where it can be determined. This is the step that catches what deduplication cannot: addresses that were once real and are not anymore.
4. Separate role accounts and catch-alls
Not everything that comes back VALID is equally useful. Role accounts (info@, support@) belong to a team, not a person, so they rarely convert even when they are real. Catch-all domains accept mail to any address whether or not it exists, so “valid” there carries less certainty. Neither needs deleting outright, but neither belongs in your highest-value send either — flag them and decide case by case.
5. Send to what is left
What remains is a list that reflects who is actually there right now, not who signed up at some point in the past. That is the list your campaign deserves to be measured against.
Skip straight to step 3
Upload your list and get format, domain, and mailbox checks back in one pass.