Migrate to a new ESP
Move sending to a new ESP with authentication, DNS, and controlled cutover.
- Difficulty:
- Advanced
- Prerequisites:
- DNS ownership, Export of templates/suppressions, Cutover window
- Last updated:
- 2026-07-15
- Author:
- empire
Objective
Migrate sending infrastructure
Move sending to a new ESP or provider without breaking authentication.
Starting state
Current ESP in production; target ESP provisioned
Prerequisites
- DNS ownership
- Export of templates/suppressions
- Cutover window
Estimated time
2–4 hours
Difficulty
advanced
Required access
- Both ESPs
- DNS
- CRM
Inputs
- Domains
- IP strategy
- Parallel-run plan
Step-by-step instructions
- Stand up the new platformConfigure domains, tracking hosts, and authentication on the new ESP first.
- Parallel sendMove a slice of traffic to validate delivery before full cutover.
- Cut over and decommissionShift remaining streams and retire old ESP credentials/DNS when stable.
Verification
- Auth passes on new ESP
- No sustained bounce/complaint spike
Common mistakes
- Cutting DNS before new auth is verified
- Keep old ESP warm as fallback for one week?
Rollback / recovery
- Return MX/tracking and sends to the prior ESP
Expected outcome
Production mail runs on the new ESP with intact authentication.
When to escalate
- Delivery collapse during cutover week