Exchange Online: Automatic Replies for Dismissed Users
Scenario
You want to be able to send customized automatic replies for the emails sent to users who have left the company and/or whose accounts no longer exist in your directory.
Solution/Workaround
Actually, there is no direct way to achieve that. However, there are some options/workarounds that can be picked depending on the situation specifically:
Senders will receive an NDR for the emails that they have sent to non-existent recipients anyway. You can accept and leave it as it is.
You can configure a transport rule to add a custom text to those NDRs after creating mail contacts for those users (you better hide them from address lists also):
- If > The recipient > is this person
- Block the message > reject the message and include an explanation
/en-us/exchange/security-and-compliance/mail-flow-rules/conditions-and-exceptions
/en-us/exchange/security-and-compliance/mail-flow-rules/mail-flow-rule-actionsBefore deleting users or unassigning their licenses, convert their mailboxes to shared mailboxes (which don't require licenses at all) and configure out of office messages for them separately. However it might become hard to control and manage them at some point.
/en-us/office365/admin/email/convert-user-mailbox-to-shared-mailbox?view=o365-worldwide