An ESP migration is a fresh start only if you do not bring the same bad list problems into the new system.
A safer migration pattern
- export the full list from the old ESP
- segment by quality or engagement where possible
- run the data through MailCull
- remove undeliverable
- import the healthier audience first
Why this matters
Your first sending behavior in a new platform matters.
If the account starts with weaker data, you are teaching the new setup the wrong lesson from day one.
What to leave behind
Migration is often the best time to stop carrying:
- dead addresses
- clearly risky segments you no longer trust
- stale subscribers with no engagement history worth preserving