Office 365 - Accessing a Shared Account via a Mobile Device
You can access a Shared Account via a mobile device using the OWA Mobile App (available for iOS, Android and Windows devices). To do this, you must first configure the shared mailbox in your UWM account with OotW (Outlook Web Access) by adding it as a shared folder.
If you have already done this, skip to Part 2 below.
Part 1: Inside the OotW (Outlook on the Web)
1. Log into your Office 365 account via OotW (Outlook on the Web) and select the Outlook tab.
2. Click on More in the left-hand pane, if you don't see your name.
3. Right-click on your name that is on the left-hand pane, and select add shared folder.
4. Start typing the name of the shared account you wish to access via a mobile device. If it does not populate as you type, you may have to hit <Enter> to search for it.
5. When you've selected the shared mailbox you wish to access, hit the add button.
6. The shared mailbox will now appear on the left-hand side underneath your mailbox.
Part 2: Inside the Outlook Mobile App
NOTE: Microsoft has not implemented support for this feature in the newest Microsoft Outlook app. You must install and configure the OWA for iPhone / Android app for your mobile device instead to view the Shared Account.
1. Open the Outlook mobile app on your device. You will be taken to your inbox as pictured below. Click on the folder icon to view your shared mailbox.
2. The shared mailbox you added earlier in OotW should now appear in your folder listing, shown here as Brian Test. From here you can review incoming mail.
3. If you wish to send a message from your shared mailbox, you must change the From: field. To do this, start composing a new message.
4. Click on the ellipses 
at the top right-hand corner of your screen.
at the top right-hand corner of your screen.5. Select show from in the menu that appears.
6. The From: field will read your email address.
7. To change this from address to the shared account, long tap on the email address inside the From field. Select remove from the menu that pops up.
8. Enter the full email address of the shared account from which you wish to send.
9. Once you have entered the From: address of the shared mailbox, you will be able to select it from the From: dropdown for future emails.