Introduction

A mailbox migration can move mail successfully while vacation replies stop completely. In many cases, the mailbox exists and receives new messages, but the autoresponder rule was not migrated, is attached to the wrong mailbox identity, or is no longer firing on the destination platform.

Treat this as a server-side mail rule problem instead of a general receive issue. Start by proving whether the mailbox is receiving normally and whether the new platform still has an active autoresponder for that exact address.

Symptoms

  • Automatic vacation replies stopped after mailbox migration
  • The mailbox receives mail normally, but senders get no out-of-office response
  • The autoresponder appears configured, but it does not trigger on new mail
  • Only some migrated mailboxes still send vacation replies
  • The issue started immediately after moving to a new mail server or provider
  • Webmail looks healthy while server-side auto-replies no longer work

Common Causes

  • The autoresponder rule was not migrated to the new platform
  • The mailbox address changed slightly and the old responder is tied to the wrong identity
  • The new server applies different sender suppression or reply-frequency limits
  • Delivery now reaches the mailbox through a path that bypasses the old filtering logic
  • The responder exists, but it is disabled or scheduled incorrectly after migration
  • Another rule or forwarding path now intercepts mail before the autoresponder runs

Step-by-Step Fix

  1. Send a fresh test message from an external sender and confirm the mailbox receives it, because you need to separate autoresponder failure from a general inbound delivery problem.
  2. Check whether the destination platform still has an active vacation responder configured for the exact migrated mailbox address, because mailbox data often moves while server-side reply rules do not.
  3. Verify the responder schedule, enabled state, and reply text on the new system, because a migrated autoresponder can exist but remain disabled or outside its active window.
  4. Confirm that the mailbox identity on the destination platform matches the intended reply address, because aliases, renamed addresses, or coexistence leftovers can attach the autoresponder to the wrong mailbox object.
  5. Review any sender suppression, duplicate-response, or reply-frequency controls on the new mail platform, because some systems intentionally limit repeated vacation replies and make the responder appear broken.
  6. Check whether forwarding, filtering, or gateway handling now touches the mailbox before local processing, because mail that bypasses local rule execution may never trigger the autoresponder.
  7. Recreate one autoresponder manually as a controlled test if the migrated rule still fails, because that quickly shows whether the issue is bad transferred rule data or a broader platform limitation.
  8. Retest from a sender that has not contacted the mailbox recently and compare results across two different external accounts, because cached suppression logic can hide whether the responder is working again.
  9. Document which mailboxes require autoresponders and how the destination platform implements them, because out-of-office rules are easy to miss during future mailbox migrations.