Migrating shared mailboxes and resource accounts

Shared mailboxes must be created in the destination tenant before migration. In Exchange Admin Center → Recipients → Mailboxes → Add shared mailbox. Create one for each source shared mailbox.

• Use the same name and email address as the source where possible.
• Shared mailboxes do not need a licence in Exchange Online (up to 50 GB). Above 50 GB requires an Exchange Online Plan 2 licence.
• Add the same members who had access in the source.

In TheMigrator, shared mailboxes appear in the mailbox mapping table alongside user mailboxes. Map each source shared mailbox to its destination equivalent. If auto-match found them, verify the mapping is correct.

Room and equipment mailboxes are resource accounts. Create them in EAC → Recipients → Resources in the destination tenant. Use the same display names and email addresses.

• Room mailboxes: set the same booking policy (auto-accept, max duration, etc.).
• Equipment mailboxes: confirm the same delegates have access.
• Calendar data will be migrated — existing room bookings will appear in the destination calendar.

After migration, confirm that delegates can still access shared mailboxes in Outlook. In the destination tenant, grant Full Access permission if it is not automatically carried over from the migration.