Forum Discussion
Dzung Vu
Aug 20, 2026Tin Contributor
Migrating from MDaemon emails to Exchange online
Dear all, Has anyone here done migrating from Mdaemon email server to Exchange Online? Can we do multi domains? can we do one user or group at a time? Any info/ help would be appreciated. Cheer...
- Aug 23, 2026
IMAP only copies mailbox data, so coexistence between MDaemon and Exchange Online requires separate mail routing.
A practical setup is:
- Keep the MX record pointing to MDaemon during the migration.
- Set the domain in Exchange Online to Internal relay, then create an outbound connector to MDaemon. This routes messages for non-migrated recipients back to MDaemon.
- After a migrated user’s final IMAP sync, configure MDaemon to route new mail for that user to their verified Exchange Online routing address, normally an onmicrosoft.com address. Check your MDaemon version’s documentation for the exact forwarding or routing setting.
- Switch the user to Exchange Online and test mail in both directions.
- After everyone has moved, update the DNS records, remove the temporary routing and change the domain back to Authoritative.
Do not create Exchange Online mailboxes too early. Once a cloud mailbox exists, Exchange Online treats that address as local instead of relaying its mail to MDaemon. Also test for routing loops before moving a real user.
Microsoft guides:
- https://learn.microsoft.com/en-us/exchange/mailbox-migration/migrating-imap-mailboxes/migrate-other-types-of-imap-mailboxes
- https://learn.microsoft.com/en-us/exchange/mail-flow-best-practices/manage-accepted-domains/manage-accepted-domains
- https://learn.microsoft.com/en-us/exchange/mail-flow-best-practices/use-connectors-to-configure-mail-flow/set-up-connectors-to-route-mail
Dzung Vu
Aug 24, 2026Tin Contributor
Hi NathanReed,
Really much appreciated your help, I'll create a test environment and do a proper plan if the project and my test approved