Disabling Direct Send in Exchange Online

Question

I'm planning to disable the Direct Send feature in Exchange. I pulled a report of messages that were sent using that feature and every one of them hit a mailbox that is forwarding to an external email address used by a legitimate service. I'd like to understand if there's something we need to do change the way these messages are forwarded so that we don't break this functionality when we disable Direct Send.

Edit to add additional detail: Nearly all of the messages are coming from external senders, which hit the forwarding rule on the mailbox and then get forwarded outbound.

Thanks

Answer 1

If the messages are being forwarded externally and not re-routed back to you, then it should be fine.

If you arent ready to disable direct send then you can use a transport rule in audit mode to see what it picked up.

https://techcommunity.microsoft.com/blog/exchange/what-is-direct-send-and-how-to-secure-it/4439865

Keep in mind that Direct Send is not really a feature or service, its simply means the messages are being send directly to the Exchange Online mx endpoint record for your domain bypassing any mx record you may have for set for a 3rd party service.