How do you make a Shared Mailbox the default Send From account? (New Outlook)

Question

I'm using Outlook for Windows version 1.2025.109.100 (on behalf of another user). 

I'm reading some suggestions online that say you need to add the account to Outlook first before making it the default Send From. I'm also looking at the Help section in Outlook that directs you to change this in the Compose and Reply settings. However, it's not possible to sign into a mailbox that isn't a user. I thought you used to be able to 'sign into' a shared mailbox using your own account but that is not the case now (perhaps it never was?).  

What it seems like is that we instead need to convert "Accounting" to a User account, give it a license, then sign into it in Outlook. That's not a Shared Mailbox - that's a user mailbox.  

I don't want to create a point of weakness for a potential cyber-attack (which we've had several). I can't really set up MFA for this account that no one can maintain. And I really don't want to have to spend money on a license to do something just because one piece of software is incompatible.  

Having to repeatedly instruct people and then repeatedly remind them to change their FROM account is just bonkers. On Outlook for Mac, as long as you're in the Shared Mailbox, the default FROM is that mailbox. (but, don't get me started on how much better the Mac version of Outlook is than the Windows version - see: All Accounts) 

Answer 1

Hi,@Jimhex2024

Thanks for posting your question in the Microsoft Q&A forum.

This functionality is not currently available for new Outlook, as it does not yet allow us to (properly) add a Shared mailbox as additional account. It's on the Roadmap and should be coming in March or so: https://www.microsoft.com/en-us/microsoft-365/roadmap?filters=&searchterms=375635

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Answer 2

Hi Jim,

In this scenario, I will recommend you to use "Outlook New" in which all the shared mailbox emails will be sent from the primary user. Please let us know if this works for you.

Thank You