Shared mailboxes in O365 (Office 365) allow a group of users to view and send e-mails from a single mailbox. Generally shared mailboxes cannot be logged into directly. You would access a shared mailbox via your own outlook by being the recipient off “Full Access” permissions
A shared mailbox should generally appear on its own after your administrator applies the permissions however, incidents may occur where the mailbox is not appearing or after having a profile re-added.
How to manually open a shared mailbox?
Ensure you are the recipient of “Full Access” permissions for that mailbox
-This is done by making a request with your mail administrator.
-(FYI) If this step was already completed and the mailbox is not showing up for whatever reason, this step does not need to be repeated. (Skip to step 2!)
Choose the File tab in the ribbon.
Choose Account Settings, then select Account Settings from the menu.
Select the Email tab
-Make sure the correct account is highlighted
-Hit on Change
Choose More Settings > Advanced > Add
Type the email address into the box (Such as Example@Example.com
Choose Ok > Ok
Chose Next > Finish > Close
-You should now see the mailbox under the Home ribbon
(PS) Make sure to click the arrow next to the mailbox to expand the folders
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