How to Add Shared Mailboxes to Outlook Mobile

Outlook Mobile Shared Mailboxes in IOS and Android – Sharing is Caring!

August 29 note: The current versions of Outlook mobile include support for shared mailboxes. See this post for details or read on to learn how to add shared mailboxes to Outlook mobile.

Last week, we learned that Microsoft will soon roll out support for shared mailboxes in Outlook Mobile. Well, some people already have access to the feature through Apple’s Testflight for iOS program. Testflight allows developers to offer test versions of applications like Outlook mobile to people who don’t mind running beta software. The upside is that you see new features sooner. The downside is that the new features might not work or might change before the final version is released. With those caveats in mind, let’s explore how to add a shared mailbox to Outlook mobile using Testflight version 3.27.0.

Add Shared Mailboxes to Outlook Mobile

Before you can add a shared mailbox to Outlook mobile, you should meet these criteria:

  • The shared mailbox must already exist on Exchange Online. Outlook mobile can only access existing shared mailboxes; it can’t create a new shared mailbox.
  • Your primary mailbox must be in Exchange Online. Users in a hybrid organization whose mailbox is on-premises can’t add shared mailboxes to Outlook mobile.
  • Your account has access to the shared mailbox. This means that an administrator assigns your account full access to the shared mailbox. In addition, if you want to send from Outlook Mobile as the shared mailbox, your account must hold SendAs permission for the mailbox.
  • You must know the primary SMTP address of the shared mailbox. Why? Because you need to input the mailbox’s SMTP address when you add the shared mailbox.

With everything in place, go to the list of resources available to Outlook mobile and click the + icon and then choose Add Shared Mailbox (Figure 1).

Add a Shared Mailbox from Outlook for iOS

Outlook mobile shared mailbox
Figure 1: Outlook Mobile Shared mailbox support (iOS)

Now input the primary SMTP address of the shared mailbox and click the Add Shared Mailbox button.

Entering the primary SMTP address to add a shared mailbox with Outlook for iOS
Figure 2: Entering the primary SMTP address to add a shared mailbox with Outlook for iOS

That’s all you need to do. Outlook Mobile adds the shared mailbox to its resource list and you can access the contents like any other mailbox.

One big benefit of native support in Outlook mobile for shared mailboxes is that it removes the need for people to use outdated protocols like IMAP4 to access shared mailboxes. From a Microsoft perspective, it gives customers another good reason to move to Outlook mobile and away from apps like the native iOS mail app that use the Exchange ActiveSync protocol to interact with mailboxes (ActiveSync doesn’t support shared mailboxes, which is why people end up using IMAP4).

Outlook Insiders and Testflight

If you want to test shared mailboxes with Outlook Mobile now, you can sign up for the Outlook Insiders program (limited slots are available). You’ll also need to download and install Testflight from the iOS app store. You can then download the test version of Outlook.

One side effect of using the test version is that Office 365 automatically provisions your tenant to use the Microsoft Sync Technology (if it didn’t, you wouldn’t be able to test new features). This process takes about 24 hours. When it’s done, you’ll be able to add shared mailboxes to your heart’s content, but only with iOS clients for now. According to a tweet from Outlook Mobile development last Friday, support for Android is coming “soon.”

Need more information about Office 365 clients, including Outlook Mobile? Read the Clients chapter in the Office 365 for IT Pros eBook!

42 Replies to “How to Add Shared Mailboxes to Outlook Mobile”

    1. Stay tuned for Microsoft’s formal announcement after all the bugs are sorted.

  1. my iPhone is running on the public version 3.32.0 however i don’t see the shared mailbox option as yet. Any changes to this?

    1. The feature is still in beta and not released for the public version of Outlook mobile.

      1. I saw in your post indicating version: version 3.27.0.and since public is already version 3.32.0 out but still without this function hence I asked if there’s any changes to the release.

      2. New versions are released every week. There’s a different between a Testflight version and a public release. You’ll have to wait for the feature to show up in a public release.

  2. During your testing, did you notice if adding a shared mailbox brings contacts from said shared mailbox?

  3. Good Afternoon
    we are having issue when tryng to add it, an authentication error shows? What is it?
    regb Biagio

  4. Will shared mailbox Calenders also be supported in Outlook for Mobile?
    Still no news on a Launch date?

  5. We still don’t see “Add shared mailbox” option on latest version of Outlook for iOS app (v 3.37.0) Is it released into production yet or still being tested?

    1. Apart from having the right version (and 3.37 is good), your tenant needs to be upgraded at the back end to use Microsoft synchronization technology.

      1. You don’t. Microsoft will enable the technology as part of its roll-out.

  6. Thanks Tony for the clarification. So any idea by when we can expect the backend to be upgraded by MS?

      1. Given the massive size of Office 365, it takes time to deploy software. And I prefer when Microsoft takes the time to fix bugs before general Availability. I have asked Microsoft for an update on the roll out and should have something to share soon.

  7. I’m running v4.0.0 of the app, I verified in app and via your powershell script that we are using the new sync technology, but I do not get the option to add a shared mailbox. What am I still missing?

      1. Ya, I must have misunderstood – I thought that once my device and backend indicated they were on the new synch technology, that that meant Microsoft had rolled it our for us. So even within a tenant there’s no way of telling what users can use the new feature until it shows up in their app one day?

      2. Nope. That’s why I quizzed Microsoft on the topic.

  8. When trying to add a shared mailbox to my outlook app i’m getting an error, and it looks like that’s because the shared mailbox is being reached through ActiveSync (as seen in the signin info logging of the shared mailbox , which we have completely blocked in our environment.
    I was under the impression that ActiveSync is borderline legacy, why are they using it now when Outlook doesn’t seem to need ActiveSync for anything else…

    1. From the Outlook team:

      The Outlook mobile app does not use ActiveSync. The cloud service (either EXO or Azure) may connect to on-premises using EAS for data sync.

      Shared mailboxes aren’t supported unless primary mailbox and shared mailbox are located in EXO.

      The fact that this commenter states “as seen in the signin info logging of the shared mailbox” tells me they are attempting to authenticate with the shared mailbox creds, meaning it’s not a shared mailbox. There is no sign-in info in a true shared mailbox scenario as the primary mailbox is already authenticated and has a token.

    1. Maybe you should report a support call to Microsoft? After all, you can complain as you like here, but it won’t do very much because this is not a Microsoft forum nor is it a route to Microsoft support.

    1. Right, unless you have Office 365 commercial licenses in which case you can file a support case. I don’t know what kind of Office 365 product people have when they post here.

  9. I think I may have found how to get it to work…
    In my case, the “Add Shared Mailbox” wasn’t showing at all even if the users can see it in their Outlook. Everything is working fine in Outlook.
    What I did is have the user logon to the OWA ( – yes we are using Exchange 365.
    Turn out that the shared mailbox doesn’t show in there it need to be added manually. After adding and then wait about 30 minutes I tried to refresh the Outlook Android App and when I tried to add a mailbox… BOOMMM! the option add shared mailbox was now there. Coincidence????? Maybe or does the OWA need to aknowledge somehow the shared mailbox so that it trigger something on the app????? Anyway it worked for me. Hope it work for someone else as well
    Thank you

    1. I guess Exchange has to know that you have permission to access the shared mailbox and that it’s one of the resources you want to use. Adding it to OWA or Outlook would refresh the list of Outlook resources, and that might have done the trick.

  10. Adding normal shared mailboxes works just fine, but if a delegate only has READ-ONLY access to a shared mailbox, the Outlook Mobile App rejects the connection with a failure message of, “Authentication Failed – that didn’t work. You may not have the right permissions to add this mailbox or this mailbox doesn’t exist”. I am authenticating with the proper account. I can connect to the shared mailbox in Outlook on workstations, but it needs to connect on the Mobile App. Any thoughts?

    1. Outlook Mobile has its own way of managing access properties. You might have to log a call with Microsoft Support on this point as it might be that Outlook Mobile assumes it has read-write access. I haven’t tried with read only access to a mailbox.

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