Email guide
Shared Mailbox Not Showing in Outlook: Permissions, Automapping and Fixes
Shared mailboxes such as accounts@ or info@ are central to how most offices handle customer and supplier email. When one fails to appear for a staff member, or they can open it but not send from it, the cause is almost always a permission that is missing, assigned the wrong way, or still propagating.
Understand the three permissions
| Permission | What it allows |
|---|---|
| Full Access | Open the mailbox and read, move and delete its items. |
| Send As | Send mail that appears to come directly from the shared address. |
| Send on Behalf | Send mail that shows “User on behalf of Shared mailbox”. |
Full Access does not include either sending permission. A user who can read the mailbox but receives an error when sending from it is usually missing Send As.
Step-by-step
Confirm the permission in the admin center
In the Exchange admin center, open the shared mailbox and review its delegation settings. Check the user is listed under Read and manage (Full Access) and, if they need to reply from the shared address, under Send As.
Allow time for automapping
When Full Access is granted directly to a user, classic Outlook adds the mailbox automatically through a feature called automapping. This can take up to an hour, and Outlook must be restarted to pick it up. If the permission was added minutes ago, waiting is the fix.
Check whether access was granted through a group
Automapping does not apply when Full Access is granted via a security group. The user still has access, but the mailbox won't appear on its own. Either grant the permission to the user directly, or have the user add the mailbox manually (step 4).
Add the mailbox manually where needed
In classic Outlook, go to File → Account Settings → Account Settings, select the user's account, choose Change → More Settings → Advanced, and add the mailbox under Open these additional mailboxes. In the new Outlook and Outlook on the web, right-click Shared with me or the account name in the folder list and add the shared folder or mailbox.
Fix sent items location
By default, messages sent from a shared mailbox may be saved to the sender's own Sent Items. Exchange Online can be configured to keep a copy in the shared mailbox's Sent Items as well, so the whole team can see what was sent. This is set per mailbox by an administrator and is worth enabling for any team mailbox.
When the shared mailbox is slow or out of date
Large shared mailboxes cached on every user's computer increase sync time and can leave folders stale. Disabling Download shared folders in the user's Cached Exchange Mode settings makes Outlook read the shared mailbox directly from the server.
Housekeeping
Review shared mailbox permissions when staff change roles or leave. Access to finance and HR mailboxes in particular should be limited to the people who currently need it.