Shared Mailboxes and 365 Outlook Web App


I have a few questions regarding shared mailboxes and Outlook on the web (365 web outlook app)

I have found some older answers online but not all answering my questions and I wanted to check if there is more up to date info.

We are in the process of migrating  large number of users from exchange 2016 to exchange online and have a number of users that use shared mailboxes (some with many , like 15 to 20 ) and many non technical users. Quite a few of the shared mailbox users will be exec level and therefore are unlikely to accept a change in functionality that is less than they have been used to - i.e. I am not looking for answers that say "you can add it manually by right clicking' or 'you can set the from field to always show  under settings '  - Im aware what is possible at the single end user level but I cant be telling people to do these things (or at most maybe one thing) as there will be too much reluctance and complaints (most sysadmins in a large organization will understand!).


I want to know if the following is possible (all from outlook web app in 365):


- Have the Outlook Web app automap any shared mailboxes the user has Full Access rights to (in testing this only seems to work with desktop outlook and not the web one so I wanted clarification if it is possible). Auto mapping it set by default  but to be sure I setup the FullAccess permission for the shared mailbox using powershell set-mailbox and applied the -Automapping $true parameter  then.


- Configure so that when a  user starts  a new message when they are in the shared mailbox (inbox or other folder)  the From field is set to the shared mailbox account and not the default user account. I.e. the most common scenario when someone is replying from a shared mailbox is to reply as that shared mailbox email but the default behavior is to use the main 365 user account in OWA 365 so will result in end user complaints.


- Automatically set for the users email compose email panel to show the FROM field when they start a new message (I know you can set it individually for users via settings but I want to set it for a large volume of users in advance - any powershell setting or scripted way to do this?)


- automatically show the available shared mailboxes that a user can Send As in the From field when they click the From button (I know once a user has used one it shows has a remembered one but we have users with 15 to 20 shared mailboxes and we are migrating them to Exchange Online and they likely cant/dont want to remember all the addresses etc). Again , powershell /scripted way to set this up?


If any of the above can be done  in the backend in a scripted way or via some kind of policy (preferably not via group policy as we have mostly been forced into a remote working scenario and dont have SCCM /MEM co-management / Hybrid Domain Join setup currently -  but if that is the way then at least would be something to work with ). The main one is probably getting the automapping working if anyone knows if that is possible.



12 Replies



I'm happy to be corrected of course, but I know of no way that you could achieve this sort of control over the settings in OWA.  I don't think what your users are asking you for is going to be possible.


Yeah, I was hoping that someone out there might know the solution to maybe one or two of these things or some inventive way of hacking it , but like yourself Im currently stumped as to how to achieve any of them.

best response confirmed by PhilRiceUoS (Contributor)

Hi @PhilRiceUoS.


I can answer only one your Q:

To permanently enable the From: field for a user execute this commandlet:

Set-MailboxMessageConfiguration user -AlwaysShowFrom $true

 To do that for all users you have to create  a small PowerShell script.

@Victor Ivanidze  - yes thankyou, I had actually found that one and after investigating thoroughly  have concluded that is the only possible one like you say.

I read through all of the related Powershell cmdlet parameters, looked through the registry settings, tried using licensed mailbox users instead of shared mailboxes but with Outlook on the Web it simply seems to have limitations currently.


Something that I do myself for my Shared Mailboxes to alleviate the lack of SM support in OWA is to make shortcut links to my SMs on my desktop. When opened it goes straight to the Shared Mailboxes' Inbox (or login 1st) and any new emails or replies I do from their is with the Shared Mailbox address.

The format of the URL is:

Of course your less technically inclined users might need some help, but it sure beats having to go the "Open another mailbox" route.

@Cary Siemers  nice for an individual level but dealing with a tenant of tens of thousands of users (only a few thousand in scope for this but still)  you can understand why im looking for just automated solutions. You can provide instructions like that of course but dealing with large user bases you are pretty much guaranteed some friction if new solutions result in a lesser experience than previously and suggesting giving "do it yourself" instructions tends to be a no starter.


My method could easily be done in a couple different semi-automated methods, but you seem to be only interested in fully automated solutions which as you've found isn't available in the current OWA.

All you can do is use Uservoice to make a suggested improvement but of course that isn't going to help you near term.

Hi again @PhilRiceUoS,


all you reuirements can be achieve easily if your users will run desktop  Outlook instead of OWA.

If OWA is mandatory try to use Office 365 groups (modern groups) instead of shared mailboxes.

@Victor Ivanidze  another good idea but one I already tried/suggested - it does in fact fulfill the automapping part as groups do auto map in OWA but the fact that you cannot create subfolders mean it was a non starter.

Hi, @PhilRiceUoS,


which of web browsers run your users? On which platform?


@Victor Ivanidze  in general Chrome on Windows 10 . I was testing using Edge (latest chromium version), firefox and chrome