What are risks during ESP migrations?

ESP migrations carry significant risk. Understanding the dangers helps you mitigate them.

Reputation risks:

New IPs need warming; sending at full volume too soon damages reputation

Domain reputation doesn't transfer if sending patterns change dramatically

Gap between old positive signals and new signals being established

Authentication gaps:

DNS records not updated correctly or promptly

SPF/DKIM failures during transition period

DMARC alignment breaking temporarily

Suppression list failures:

Bounced addresses not imported; you email them again and damage reputation

Unsubscribes missing; you email opted-out recipients (compliance issue)

Complaints not transferred; repeat offenders complain again

Data continuity:

Historical engagement data lost or not transferred

Subscriber preferences and segments not migrated correctly

Tracking links in old emails break

Technical disruptions:

Automations not replicated correctly

Integration points not updated (forms, APIs, CRM connections)

Webhook endpoints changed

Timeline pressure:

Rushing due to contract deadlines

Not allowing adequate warmup time

Insufficient testing before go-live

Plan for these risks with checklists, testing phases, and adequate timeline buffers.