UPDATE NOV 1, 2022: Cross-tenant mailbox migration is now generally available! See Cross-tenant User Data Migration is Now Generally Available for details.
Historically, wh...
Updated Jan 07, 2025
Version 10.0
Blog Post
Hello,
I have managed all migration steps and migrated one test mailbox. In source tenant mailbox was converted to mail user and in destination tenant mail user was converted to mailbox. Connected to Outlook with new UPN, everything are migrated. There are no problem with getting mails also. Problem is with mail sending. When I send mail, recipient gets mail from @destinationcompany.onmicrosoft.com. Is it possible somehow force sending from @sourcecompany.com ? I can't add source domain as proxy address. Destination tenant is synchronized with AD sync. If I add additional proxy address with source domain in AD user properties it does not sync. Maybe I need additional connector or some kind of forward? I made configuration by this article: https://docs.microsoft.com/en-us/microsoft-365/enterprise/cross-tenant-mailbox-migration?view=o365-worldwide
There are known issue: ssue: MailUser objects with "external" primary SMTP addresses are modified / reset to "internal" company claimed domains". This is exactly my situation. But if I remove Exchange online license from user, mailbox disappears from exchange.
Any suggestions?