How to move sender reputation between ESPs?

Reputation doesn't transfer directly between ESPs, but different components behave differently during migration.

Domain reputation:

Stays with your domain regardless of ESP

Continues from previous sending history

Transfer is automatic if you use the same domains

Dramatic pattern changes may still affect it

IP reputation:

Stays with the old IPs; doesn't transfer

New ESP means new IPs that need warming

Start from scratch building IP reputation

This is the biggest migration challenge

Strategies to preserve reputation:

Gradual migration: Split traffic, slowly shifting volume to new ESP as its IPs warm

Prioritize engaged recipients: Send to most engaged subscribers first from new ESP

Maintain consistency: Keep sending domains, patterns, and content similar

Don't go dark: Gaps in sending hurt reputation; maintain regular cadence

What you can transfer:

Suppression lists (protect from re-damaging reputation)

Engagement data (to segment for warmup)

Best practices and learnings

Documentation of what worked

Your domain's logbook travels with you; the ship's reputation stays with the ship. New vessel means proving yourself again at every port.