How to Migrate an Application That Uses a Third-Party SMTP Relay

A host move can change source IPs, TLS behavior, DNS, or relay authentication and cause application email to stop.

Checks to make

Inventory relay host, port, authentication method, sender policy, and IP allowlists. Test from the target environment with controlled messages, verify SPF and DKIM alignment, and monitor provider responses during cutover.

When to get help

Cloud migration support can trace relay dependencies and mail delivery. Informatix Systems can assess the symptoms, evidence, and next steps. Contact Informatix Systems to discuss this issue.