Receive error: Target mailbox doesn't have an SMTP proxy matching '.mail.onmicrosoft.com' when move mailbox to Office 365
Recently I was working on Exchange Hybrid Deployment for one of our customer. The Hybrid Configuration process itself went smoothly. No errors for HCW. The problems came when I tried to move mailbox to Exchange Online. The migration fails with error: Target mailbox doesn't have an SMTP proxy matching '<domain>.mail.onmicrosoft.com'" To check that I ran the following command against the On-premise Exchange. Get-Mailbox "O365 Test5" | fl and check the EmailAddress filed Then I ran get-mailuser in Exchange Online. Because the mailbox hasn't been migrated, the user still show up as Mailuser(Contact) in Office 365. Get-MailUser "o365 test6" |fl Noticed the proxy address "contoso.mail.onmicrosoft.com" does not show up into the Azure AD object. The user object in Office 365 only has our primary SMTP address "username@contoso.com" and "username@contoso.onmicrosoft.com" stamped. "CONT