Changing "From" info on Message Headers in Transport Rules of M365 environment

Question

Hi,

I need help about a scenario in M365 Mail settings. There is a mailbox named @test.com and this is configured in one of the applications' Outgoing Mail Settings. This application uses this e-amil address to send emails to the clients for specific conditions. Our goal is to change the "From": Email Address (@test.com) section on message headers before reaching these emails to the client. So, let's say there is another mailbox named ******@test.com. The scenario;

When ******@test.com sends an email to clients with specific keywords in their subjects, this mail should be sent by ******@test.com as checking two conditions in the Rules on M365;

1- Mail sent from ******@test.com

2- Subject contains specific word like "test-1"

(there is no problem till here)

If these conditions are met, the rule should set a message header that this mail is sent from ******@test.com (as removing ******@test.com value).

Can this modification be done in Transport Rules in the M365? I couldn't understand how to setup message header (if it's possible to do so).

Regards,

Answer 1

What you are asking for is effectively address rewriting, and it's not supported in Exchange Online. Though you should be able to address the scenario above by simply using Send As permissions/Send on behalf of.

Answer 2

Hi @ Melih ÇINAR ，

Yes, Exchange Online doesn't support rewriting email addresses during message transfer.

You could refer to the following link to assign the send as /send on behalf permission. When you need to, you can choose to send notification emails on behalf of this mailbox:

 

 Manage permissions for recipients in Exchange Online | Microsoft Learn

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