How to Add a Shared Mailbox in Outlook

A shared mailbox lets a team read and send email from a common address (e.g., [email protected]) without buying a separate licence. You’ll need two things:

1. Permission (at least Full Access to open it; Send As or Send on Behalf if you need to send).
2. The right add method (some auto-map, some need manual add).

If you don’t see the mailbox after following the steps, jump to Troubleshooting.

First: do you already have permission?

• If IT has granted Full Access, Outlook often auto-maps the mailbox after you restart Outlook (desktop) or refresh your session (web).
• If you also need to reply as that mailbox, ask for Send As (not just “on behalf of”, unless that’s what you want).

If you’re unsure, try adding it. If it fails, ask IT to confirm your permissions on the mailbox.

Outlook on the Web (Outlook.com / Microsoft 365 online)

Option A — Open it temporarily (opens in a new tab/window)

1. Go to Outlook on the web.
2. Click your profile picture (top-right) → Open another mailbox.
3. Enter the shared mailbox name/address (e.g., support@…) → Open.

Option B — Add it to your folder list (stays on the left)

1. In the left folder pane, right-click your name (or your primary mailbox).
2. Choose Add shared folder or mailbox.
3. Type the shared mailbox name/address → Add.
   You’ll now see the shared inbox/folders pinned under your own.

Send From the shared mailbox (web)

• Compose a new email → click From → choose the shared address (if not visible, choose Other email address and search it).
• It will remember this choice next time.

Outlook for Windows

There are two Windows experiences: New Outlook (modern app) and Classic Outlook (rich client with ribbon). If you’re unsure, the classic one has File > Account Settings menus.

A) New Outlook for Windows

1. Click the cog (Settings) → Accounts → Email accounts.
2. Shared mailboxes → Add shared mailbox.
3. Enter the shared mailbox address → Add.
4. It appears in the left pane. Restart the app if it doesn’t.

Send From: New message → From → select the shared address.

B) Classic Outlook for Windows (Microsoft 365 Apps)

If it auto-mapped: just restart Outlook; it appears under your folders.
Add manually (if it didn’t auto-map):

1. File → Account Settings → Account Settings…
2. Select your account → Change → More Settings…
3. Advanced tab → Open these additional mailboxes → Add…
4. Type the shared mailbox name/address → OK → OK → Next → Finish → Close.
5. Restart Outlook. The mailbox shows in the left pane.

Send From: New Email → Options → tick From (shows the From line) → pick the shared address (or Other Email Address… and search).

Outlook for Mac

There’s a New Outlook (toggle in the top-right) and the legacy/classic experience.

A) New Outlook for Mac

1. Outlook → Settings → Accounts.
2. Select your work account → Delegation and Sharing.
3. Shared With Me tab → + → search and select the shared mailbox → Add.
4. It appears in the left pane. If not, restart Outlook.

Send From: New Message → From (toggle it if hidden) → choose the shared address.

B) Legacy/Classic Outlook for Mac

1. Tools (or Outlook menu) → Accounts…
2. Select your work account → Advanced…
3. Delegates tab → under People I am a delegate for, click + → add the shared mailbox → Add → OK.
4. Close settings; the mailbox appears in your folder list after a short sync (or restart Outlook).

Outlook Mobile (iOS/Android)

There are two approaches on mobile:

Option 1 — Add it as a shared mailbox (supported in most current builds)

1. In Outlook mobile, tap your profile icon (top-left) → Settings (cog).
2. Under Mail accounts, tap your work account → Add Shared Mailbox.
3. Enter the shared mailbox address → Add Shared Mailbox.
   It appears under your account with its own Inbox/Sent/Archive.

Option 2 — Add as another account (only if it has its own licence/password)

• If IT created the shared mailbox as a full user (rare), you can add it as a separate account with its password. Most shared mailboxes don’t have their own password, so prefer Option 1.

Send From (mobile): Compose → tap the From address → pick the shared mailbox.

What’s the right “send” permission

• Send As: Recipients see the email from the shared mailbox (e.g., Support).
• Send on Behalf: Recipients see “Your Name on behalf of Support”.
  Ask IT for the one you need—Send As is most common for team addresses.

Admin corner (for the person managing Microsoft 365)

1. Create the shared mailbox
   • Exchange Admin Center → Recipients > Shared → Add a shared mailbox.
2. Grant access
   • Assign Full Access (open/read) and Send As (if needed) to the users or groups.
3. Auto-mapping
   • If you assign Full Access directly to users (not via a group), Outlook desktop usually auto-maps the mailbox. Group-based permissions may not auto-map—users can add it manually.
4. Mobile access
   • No licence is required for a traditional shared mailbox (≤50GB, no direct login).
   • If you plan to sign in directly on mobile or use it with apps that need a password, you’ll need a licence and a proper user mailbox instead of “shared”.

Troubleshooting (quick fixes)

• “The set of folders cannot be opened” / can’t add mailbox
  • You probably lack Full Access permission. Ask IT to verify in Exchange Admin Center.
• I can see the mailbox but can’t send from it
  • You need Send As (or Send on Behalf). Ask IT to add it; restart Outlook after changes.
• It’s not auto-mapping in desktop Outlook
  • Close Outlook, wait 5–10 minutes, reopen. If still missing, add it manually (see steps) or ask IT to re-grant permissions directly to your user (not via group) if auto-mapping is required.
• From address doesn’t appear when composing
  • In desktop Outlook, show the From field (Options → From). In web/mobile, tap/click From to switch.
• Sent Items go to my personal Sent, not the shared mailbox
  • Desktop Outlook:
    • File → Account Settings → Account Settings → select your account → Change → More Settings… → Advanced tab → under Sent Items, tick “Sent items for shared mailboxes go to the shared mailbox Sent Items” (wording varies), or set this via mailbox features/admin policy.
  • In Exchange Online, admins can enable Copy to Sent Items for shared mailboxes.
• Search is slow or misses results
  • Let the new mailbox finish indexing. In Classic Outlook, ensure it’s in Cached Exchange Mode (File → Account Settings → Account Settings → double-click account → tick Cached).
• Mobile app can’t add shared mailbox
  • Update Outlook mobile to the latest version. If still no option, remove/re-add your main account, then try Add Shared Mailbox again.

Good practice for teams

• Use the shared mailbox’s address for replies so customers see a consistent From.
• Turn on “Save Sent Items in Shared Mailbox” so the team can see what’s been sent.
• Create categories or folder rules for quick triage (e.g., “Billing”, “Sales”, “Urgent”).
• If volumes grow, consider upgrading to a Microsoft 365 Group + shared mailbox, or a lightweight ticket tool inside Teams.

Quick checklist (printable)

• I have Full Access (and Send As if I need to send).
• Added the mailbox in Outlook on the web or desktop (per steps above).
• From shows the shared address when I compose.
• Sent Items from the shared mailbox go to the shared Sent, not mine.
• Team agreed simple filing rules (categories/folders).