Shared Mailbox send on behalf doesn't work correctly: Manually selection is required

Question

Dear,

We are gradually making the switch to shared mailboxes. However, that does not go exactly as desired. We want to grant send on behalf, so Outlook will display "User_Name send on behalf to Team ICT" when sending an email from a shared mailbox.

After a lot of troubleshooting, we finally managed to find a workaround where it does work (see the attachmentfor the step-by-step plan of screenshots). However, this is not a solution. In other M365 environments this worked automatically, and you do not have to do this manually if you want to send an email from a shared mailbox.

Full Access and Send on behalf rights are also granted. I also tried Send As, but it doesn't seem to be necessary, so I turned it off again. We are looking for a structural way to have this applied automatically by our users. Of course, the steps we are going through now cannot be sold to our users. Especially because I have seen it work automatically in previous environments.

Answer 1

Hello Cas B,

Good day! Thank you for posting to Microsoft Community.

I understand that you're experiencing issues with sending emails on behalf of a shared mailbox.

Based on your description, it looks like you need the shared mailbox address to be automatically added to the From field in a new email. I did some tests on my end as well and noticed that outlook will use the address assigned to the currently selected mailbox or data file as the default address if it is configured as an account in File, Account Settings. Because a shared account is a secondary account in your profile, Outlook won’t use that address by default when viewing the mailbox. Looks like a design behavior. Open and use a shared mailbox in Outlook - Microsoft Support.

You can go around this by adding the shared mailbox to your profile as a mailbox. You may however need remove delegate permissions or disable automapping before you add it to your profile.

In case I misunderstood you in anyway, please let me know.

Looking forward to your response.

Best Regards,

Ashraf.

Answer 2

Dear Ashraf,

Thank you for your response. It worked for me to automatically send on behalf of a mailbox by deleting my '2nd' mailbox in my account settings, because this email is no longer a user mailbox. Then I followed the step-by-step instructions ( https://support.microsoft.com/en-us/office/open-and-use-a-shared-mailbox-in-outlook-d94a8e9e-21f1-4240-808b-de9c9c088afd)

Then I could choose from 'from' (the shared mailbox) to send on behalf of the mailbox, but is there a way to push this to all users in my environment?

Answer 3

Dear Cas B,

Thank you for your response.

After further tests, I'm afraid I couldn't find a way around to push this. Mainly because the user profiles are rather local and not admin controlled. Unless you remove auto-mapping from the shared mailbox and the users add this shared mailbox as another account. I honestly wish I had a better idea.

Thank you for your kind understanding.

Best Regards,

Ashraf.