A Microsoft 365 shared mailbox is opened from your own account. You never sign in to it directly. An admin adds you as a member, you restart Outlook, and in the Windows clients the mailbox appears in the folder pane on its own. When it does not, each Outlook client has a manual path, and they are all below.
Ask your Microsoft 365 admin to add you as a member, then restart Outlook. In new and classic Outlook for Windows the mailbox appears on its own. If not, right-click your account name and choose Add shared folder or mailbox (new Outlook and web). Classic: File > Account Settings > Change > More Settings > Advanced > Add. Mac: File > Open > Shared Mailbox. Phone: Add Account > Add a Shared Mailbox.
How do you add a shared mailbox in Outlook?
The process has two halves. An admin grants you Full Access to the shared mailbox in the Microsoft 365 admin center or the Exchange admin center. Then Outlook, on whichever device you use, connects to that mailbox through your own account. Microsoft calls the automatic half automapping: Outlook reads the permissions on your mailbox and opens every mailbox you have Full Access to.
Automapping is on by default, but it only works when the permission is granted to you directly. If your admin granted access through a security group, nothing appears and you need the manual steps. Automapping also does not exist in Outlook for Mac. Those two facts explain a large share of the searches for a shared mailbox that is not showing. Both come from Microsoft's Create a shared mailbox page.
If you are the admin and the mailbox does not exist, start with how to create a shared mailbox in Microsoft 365. The rest of this guide assumes the mailbox exists and you are a member.
Add a shared mailbox in new Outlook for Windows
New Outlook is the client with the toggle in the top right corner and no File menu. After your admin adds you, close and reopen it. The shared mailbox should appear in the folder pane. Microsoft's guidance is that a recent membership can take a few minutes to show, so wait, then restart once more before adding it by hand.
- Select Mail in the navigation pane.
- In the folder pane, right-click your account name and select Add shared folder or mailbox.
- Type the shared mailbox address, for example support@yourcompany.com, and confirm.
- Expand the Shared with me folder in the folder pane. The shared mailbox is listed there as a subfolder, with its own Inbox and Sent Items.
Steps verified October 2026 against Open and use a shared mailbox in Outlook. The same page covers the From field, which is the subject of how to send email from a shared mailbox.
Add a shared mailbox in classic Outlook for Windows
Classic Outlook has the File menu and the full ribbon. Automapping applies here too, so the first move is a restart. If the mailbox is still missing, add it to your Exchange account profile.
- Select File > Account Settings > Account Settings.
- On the Email tab, select your account and choose Change.
- Select More Settings > Advanced > Add.
- Type the shared mailbox address, then choose OK > OK.
- Choose Next > Finish > Close. The shared mailbox appears in the folder pane under your own mailbox.
The shared calendar and contacts come with it. After the restart, pick the shared mailbox in Calendar view, or look under My Contacts in People.
Add a shared mailbox in Outlook on the web
Outlook on the web does not automap. There are two documented ways in, and they behave differently.
- In the folder list: right-click Folders (for Exchange on-premises, right-click your primary mailbox name instead), select Add shared folder or mailbox, and enter the shared mailbox address. It appears beneath your own folders. To remove it later, right-click it and select Remove shared folder.
- In its own window: select your name or picture on the navigation bar, choose Open another mailbox, type the address and select Open. A second Outlook on the web window opens with only the shared mailbox in it.
Microsoft notes that new-message notifications for the shared Inbox only fire in the separate-window method. The separate window is also where inbox rules for the shared mailbox are created. That matters for the practices in shared mailbox limits, licensing and best practices. Steps verified October 2026 on Add a shared mailbox to Outlook on the web.
Add a shared mailbox in Outlook for Mac
Outlook for Mac supports Full Access only, with no automapping, so the mailbox never appears on its own. Microsoft documents three routes on Open a shared Mail, Calendar or People folder in Outlook for Mac, verified October 2026.
- File > Open > Shared Mailbox, then search for the mailbox and open it.
- Tools > Accounts, select your account, choose Delegation and Sharing, open the Shared With Me tab and select the plus button to add the mailbox.
- Add it as an account: Tools > Accounts, select the plus button to add an Exchange account, enter the shared mailbox address, and enter your own credentials under Authentication. Turn on Sync shared mailbox so it updates without a manual Send/Receive.
Use the third route when you want the shared mailbox to behave like a full account. It gets its own folder tree and its own Sent Items in the sidebar. It needs Full Access set in the Exchange admin center, which an admin can grant in a minute.
Add a shared mailbox in the Outlook mobile app
The Outlook app on iPhone and Android can hold a shared mailbox next to your own account. Both mailboxes must be in Exchange Online and use Microsoft's native sync, which is the case for any ordinary Microsoft 365 tenant. Steps verified October 2026 on Add a shared mailbox to Outlook mobile.
- Sign in to your primary work account in the Outlook app.
- Tap the Add Account button in the left navigation pane, then tap Add a Shared Mailbox.
- If you have more than one account, choose the one that has access to the shared mailbox.
- The shared mailbox appears in your account list. To remove it later, go to Settings > Accounts, tap the shared mailbox and select Delete Account.
Microsoft's admin documentation adds one detail. A shared mailbox can only be added to the Outlook for iOS and Android apps, so the built-in Mail apps are out. The alternative on a phone is Outlook on the web in the browser.
Why the shared mailbox is not showing in Outlook
When the mailbox stays hidden after a restart, work down this list. Each cause is specific and each has a fix.
- You were added minutes ago. Microsoft says a new membership can take a few minutes to appear. Wait, restart Outlook, then add it manually if it is still missing.
- Permission came through a security group. Automapping is written to your own mailbox when Full Access is granted to you by name. Group-based access does not trigger it. Ask the admin to grant the permission directly, or add the mailbox manually.
- You are on a Mac or on the web. Neither automaps. Use the manual steps above.
- The mailbox is hidden from the global address list. Microsoft's configuration notes say new members cannot add a hidden shared mailbox to their Outlook profile until it is shown again. The admin toggles this under Show in global address list.
- You have Send As but no Full Access. Send permissions let you send from the address; only Full Access opens the mailbox. Ask which permissions you hold.
- You can see it but cannot send. The error about not having permission to send on behalf of the specified user, right after a membership change, is replication latency. Microsoft's guidance is to wait about an hour and try again.
- An admin turned automapping off. Some organizations disable it for people with Full Access to many mailboxes, because Outlook opens every one at startup. The admin can check with Add-MailboxPermission and the AutoMapping parameter. Both are documented on Remove automapping for a shared mailbox.
If you can open the mailbox but your sent replies vanish into your personal Sent Items, that is a setting rather than a fault. The admin fix is in how to send email from a shared mailbox.
Where a shared mailbox stops for a team
Adding the mailbox to every client is the easy part. Once five people are reading the same Inbox, the questions change: who is handling this thread, has anyone replied, and what did we promise this client in March.
A shared mailbox is built for a front desk. It has no owner field, no internal notes and no record of who read what. Teams simulate ownership with categories named after people and a weekly reminder to check them.
We build Sektra, a separate shared inbox workspace that syncs two-way with Microsoft 365, including shared mailboxes. The shared mailbox stays in Microsoft 365 and categories map to tags. Every thread gets an owner, internal notes and a typing indicator that reads 'A teammate is typing a reply'. Outlook connects through Microsoft sign-in, and Sektra never sees that password.
The Outlook integration page covers the setup, and connect an Outlook shared mailbox walks through the consent step. For the longer version, read where an Outlook shared mailbox stops and a shared inbox tool starts. Customer success teams, who live in exactly this kind of inbox, have their own page at Sektra for customer success.
