We have recently seen an issue reported whereas following on from the mailbox restore process being carried out on a user account, external users are receiving a bounce-back when trying to email them. When checking the user account in the Exchange Admin portal, we can see exchange errors on the user account, despite the mailbox being created successfully. This issue seems to occur predominantly for user accounts who require their soft deleted mailbox restored due to other exchange issues they are currently experiencing.

What we tend to see is, following on from the mailbox restore, the proxy addresses and target address of the user are as they were previously, which suggests emails should be received successfully. However, the user account is recreated in the Exchange Management Console with the ‘Recipient Type Details’ field showing as ‘Mail User’ rather than ‘Remote User Mailbox’.

In order to resolve the errors seen in the Exchange portal, and for emails to be received successfully, follow the steps outlined below:

 

  1. Load up the Exchange Management Shell
  2. Run the command:
  • Set-AdServerSettings -ViewEntireForest $True
  1. Run the command:
  • Enable-RemoteMailbox “user@domain.com” -RemoteRoutingAddress “user@domain.mail.onmicrosoft.com”

 

Once this has completed, check the Exchange Management Console and the user’s ‘Recipient Type Details’ field should now show as ‘Remote User Mailbox’ rather than ‘Mail User’.

If we check in the portal, the Exchange errors previously seen should no longer be there. It is also worth sending a test email from an external email address to check that a bounce-back is now longer received.