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 ‘.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