Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hello SITN-AH,
According to my experience, there are 2 methods to manage message approval in Exchange Online, one is changing the Distribution group properties. Another one is creating a mail flow rule.
I have done many tests both using the 2 methods above but didn’t find any method to send a notification email to the sender when the email is approved. As a workaround, it is suggested reply to the sender manually.
Besides, you can submit the idea in Office 365 UserVoice forum. Microsoft pays high values on customer’s feedback and it helps improved the user experience.
Your understanding and cooperation are highly appreciated.
Regards,
Rick