Microsoft Clamps Down on Automatic Mail Forwarding in Exchange Online



Microsoft has updated the Exchange Online outbound spam filter policy to stop automatic forwarding of email from user mailboxes. The change is now effective with the default set to block automatic forwarding. You can create a custom policy and apply it to selected mailboxes and distribution lists if they need to forward email.

4 Replies

Hi @Tony Redmond 


Before this change, I controlled auto forwarding via a mail flow rule. In this rule I allowed mail forwarding for a specific group of people, but also for a specific recipient domain (

Reason for this was a use case where someone wanted to auto-forward incoming tender mails to specific teams channels, based on the sender of the incoming mail (apparently it's a 1-to-1 relation).

This worked fine until Microsoft flipped the switch but in the new outbound spam policy, under the conditions, I can only set conditions for 'sender is' or ' sender domain is' but I don't want him to be able to auto-forward to just anywhere, I want him to be able to auto-forward only to a specific destination domain.

How can I achieve this within the new rules? :) 

@Steve Hernou  You can always revert to the previous behavior and allow mail forwarding by all users and use your mail flow rule as before. The point about the change is that it improves the security of tenants where people might not have thought through the ramifications of auto forwarding. You have because you have built a rule to control the process, so why not just go back to it?

@Tony Redmond , aha, looks like I misinterpreted the change. I thought the new system negated the mail flow rule option and you had to use the outbound spam policy now.

So I can just set the default anti-spam policy to allow auto forwarding and then still my mail flow rule will be enforced and block all except what's defined in the mail flow rule.

Thank you very much for the clarification :)

Thanks for the information, Tony. I have been questions about why some rules are no longer working as expected