Mailbox migration between providers: preserve identity, replies and suppression

Define the decision

A provider migration can change MX routing, SMTP endpoints, DKIM selectors and IMAP identifiers. Recreating an account without a plan can also leave queued work tied to an old connection or make reply history difficult to reconcile.

Work through the procedure

1. Inventory active campaigns, mailbox ownership and pending replies.
2. Prepare the new provider’s authentication and DNS while preserving a rollback path.
3. Pause affected sends during the controlled cutover.
4. Connect and verify the new send-and-reply path.
5. Review active enrollments, suppression and historical context before resuming.

Worked example

The following is a synthetic example for this procedure, not a customer result or performance benchmark.

Cutover checklist: new provider configured → DNS validated → controlled send accepted → controlled reply visible → campaign mailbox selection reviewed
Preserved data: opt-outs, bounce history and unresolved conversations

Read the result

The verification gate covers both transport directions and application state. A successful incoming MX test does not establish that the campaign uses the new SMTP identity.

Check before moving on

1. Account for UIDVALIDITY changes and rescans.
2. Keep the old connection available only as long as the approved rollback plan requires.

Limits and next action

Do not delete the old mailbox or application records before validating the migration. Provider-specific mailbox transfer procedures remain the administrator’s responsibility.

Source: Zintara mailbox and inbox workflow context