A shared mailbox gives a group of people access to a common email address — like info@yourcompany.com or support@yourcompany.com — without requiring a separate license or password. Everyone with access can read, reply to, and send emails from the shared address, and all the conversations stay in one place.

Creating a shared mailbox requires Microsoft 365 admin access. If you’re not an admin, you’ll need to ask your IT department or Microsoft 365 administrator to set one up and add you as a member. Once it’s created, any member can add it to their own Outlook client.

This guide covers the full process: creating the mailbox, adding it to Outlook (desktop and web), managing permissions, and sending from the shared address.

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Quick Reference

Task	Where to Do It	Who Can Do It
Create a shared mailbox	Microsoft 365 admin center → Teams & groups → Shared mailboxes	Admin only
Add members	Microsoft 365 admin center → select the mailbox → Edit members	Admin only
Add to Outlook desktop (new)	Happens automatically after being added as a member	Members
Add to Outlook desktop (classic)	File → Account Settings → Change → More Settings → Advanced → Add	Members
Add to Outlook on the web	Right-click Folders → Add shared folder	Members
Send as the shared mailbox	New email → From field → select the shared address	Members with Send As or Send on Behalf permission
Set permissions	Microsoft 365 admin center → select the mailbox → Manage email settings	Admin only

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1. Create a Shared Mailbox in the Microsoft 365 Admin Center

Only Microsoft 365 admins (Global admin or Exchange admin) can create shared mailboxes.

1. Sign in to the Microsoft 365 admin center.
2. In the left navigation, expand Teams & groups and select Shared mailboxes.
3. Click + Add a shared mailbox.
4. Enter a Display name (e.g., “Customer Support” or “Sales Inquiries”). This is the name people will see in their address book.
5. Enter an Email address (e.g., support@yourcompany.com). The domain dropdown will show your organization’s verified domains.
6. Click Save.
7. Under Next steps, click Add members to this mailbox.
8. Click + Add members, select the people who should have access, then click Add.
9. Click Close.

The shared mailbox is now live. Members will be able to access it in Outlook within an hour (sometimes faster, sometimes up to 24 hours for the auto-mapping to propagate).

Storage: Shared mailboxes get 50 GB of storage without requiring a separate license. If you need more than 50 GB, you’ll need to assign an Exchange Online Plan 2 license (or an Exchange Online Plan 1 license with an Exchange Online Archiving add-on) to the mailbox.

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2. Add a Shared Mailbox to Outlook Desktop

New Outlook for Windows and Mac

If you’ve been added as a member by an admin, the shared mailbox should appear automatically in your left sidebar within about an hour. You’ll see it listed as a separate account below your primary mailbox.

If it doesn’t appear:

1. Click your profile icon in the top-right corner.
2. Click Add account.
3. Enter the shared mailbox’s email address and follow the prompts.

Classic Outlook for Windows

Classic Outlook uses auto-mapping by default — if the admin enabled it (it’s on by default), the shared mailbox will appear automatically in your folder pane after you restart Outlook.

If auto-mapping isn’t working or was disabled, add it manually:

1. Go to File → Account Settings → Account Settings.
2. On the Email tab, select your Exchange account and click Change.
3. Click More Settings.
4. Go to the Advanced tab.
5. Click Add under the “Open these additional mailboxes” section.
6. Type the name or email address of the shared mailbox and click OK.
7. Click OK → Next → Finish → Close.
8. Restart Outlook. The shared mailbox will appear as a separate folder tree in your left pane.

Outlook for Mac (Classic)

1. In Outlook, press Cmd + , to open Preferences (or go to Outlook → Settings).
2. Click Accounts.
3. Select your Exchange account, then click Delegation and Sharing.
4. Under Shared with me, click the + button.
5. Type the shared mailbox email address and click Add.
6. The shared mailbox appears in your folder pane.

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3. Add a Shared Mailbox to Outlook on the Web

1. Go to outlook.office.com and sign in.
2. In the left pane, right-click on Folders (or right-click on your mailbox name).
3. Select Add shared folder (or Add shared mailbox — the label varies).
4. Type the name or email address of the shared mailbox.
5. Select it from the suggestions and click Add.

The shared mailbox appears as a separate folder tree in your left pane, below your primary mailbox. You can expand it to see its Inbox, Sent Items, Drafts, and any subfolders.

To remove it later, right-click the shared mailbox in the folder pane and select Remove shared folder.

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4. Manage Shared Mailbox Permissions

Shared mailboxes support three types of access, all configured in the Microsoft 365 admin center.

Full Access

Granted automatically to all members. Lets a user open the shared mailbox and read, delete, and organize emails — but not send from the shared address.

Send As

Lets a member send emails that appear to come directly from the shared mailbox address. The recipient sees support@yourcompany.com in the From field with no indication that a specific person sent it.

Send on Behalf

Lets a member send emails on behalf of the shared mailbox. The recipient sees something like “Jane Doe on behalf of support@yourcompany.com” in the From field.

How to Assign Send As or Send on Behalf Permissions

1. Go to the Microsoft 365 admin center.
2. Navigate to Teams & groups → Shared mailboxes.
3. Select the shared mailbox.
4. Under Email settings, click Manage email settings.
5. Click Edit next to Read and manage (Full Access), Send as, or Send on behalf.
6. Click + Add permissions, select the users, and click Save.

Changes typically take effect within 30 to 60 minutes.

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5. Send Email from a Shared Mailbox

Once you have Send As or Send on Behalf permissions, you can send emails that appear to come from the shared mailbox address.

Outlook on the Web

1. Open a new email.
2. Click the From field. If you don’t see a From field, click the three dots (…) in the toolbar and select Show From.
3. Click From and select Other email address.
4. Type the shared mailbox email address and select it.
5. Compose your message and click Send.

Outlook will remember the shared address — next time, it will appear in the From dropdown.

New Outlook Desktop

1. Open a new email.
2. Click the From field at the top of the compose window. If From isn’t visible, click … → Show From.
3. Select the shared mailbox address from the dropdown, or type it in and select it.
4. Compose and Send.

Classic Outlook for Windows

1. Open a new email.
2. If the From field isn’t visible, click the Options tab in the ribbon and click From.
3. Click From → Other Email Address.
4. Type the shared mailbox email address, or click From to browse the address book.
5. Compose your message and click Send.

Tip: Replies sent from the shared mailbox are stored in the shared mailbox’s Sent Items folder, not in your personal Sent Items. This keeps the shared mailbox’s conversation history complete for all members.

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6. Shared Mailbox vs. Distribution List vs. Microsoft 365 Group

These three features overlap in ways that cause confusion. Here’s when to use each.

	Shared Mailbox	Distribution List	Microsoft 365 Group
What it is	A mailbox that multiple people can open, read, and send from	A mailing list that forwards emails to all members’ individual inboxes	A collaboration workspace with a shared mailbox, calendar, file library, and optional Teams channel
Shared inbox	Yes — one inbox everyone accesses	No — emails go to each member’s personal inbox	Yes — but most people interact with it through Teams or Outlook groups
Send from the shared address	Yes (with Send As or Send on Behalf permissions)	No — members reply from their own addresses	Yes (with Send As permission), but less common
Requires a license	No (up to 50 GB)	No	No
Requires admin to create	Yes	Distribution groups: Yes. Contact lists: No (any user)	Depends on org settings; usually any user
Calendar	Yes — has its own calendar	No	Yes
Shared files	No	No	Yes — SharePoint site included
External members	Can receive email from external senders; external users can’t access the mailbox	Can include external email addresses	Can add external guests
Best for	Shared email addresses (support@, info@, billing@) where the team needs to see and manage all messages in one place	Broadcasting announcements or newsletters to a group — no shared access needed	Team collaboration with shared conversations, files, calendar, and optional Teams integration

Rule of thumb:

• Need a shared inbox that multiple people manage? Shared mailbox.
• Need to send the same email to a list of people? Distribution list.
• Need shared files, calendar, and conversations for a team? Microsoft 365 Group.

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7. Shared Mailbox Settings Worth Configuring

After creating the shared mailbox, there are a few settings admins should review.

Auto-replies (Out of Office): You can set up automatic replies for the shared mailbox. In the admin center, select the mailbox, click Manage email settings, and configure auto-replies under Automatic replies. Alternatively, a member can set them from Outlook on the web by opening the shared mailbox and going to Settings → Mail → Automatic replies.

Sent Items behavior: By default, emails sent from the shared mailbox are saved in the shared mailbox’s Sent Items folder. If they’re going to the sender’s personal Sent Items instead, an admin can fix this by running this Exchange Online PowerShell command:

Set-Mailbox <SharedMailboxName> -MessageCopyForSentAsEnabled $true -MessageCopyForSendOnBehalfEnabled $true

Conversion to a regular mailbox: If someone leaves and you want to convert a shared mailbox to a regular user mailbox (or vice versa), you can do this in the admin center under Teams & groups → Shared mailboxes → select the mailbox → Convert to regular mailbox. This requires assigning a license.

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If you manage shared inboxes across tools, Carly is an AI assistant that connects to 200+ apps — including Outlook, Gmail, Slack, and your CRM — to help you stay on top of messages, automate replies, and keep nothing slipping through the cracks.

More on Outlook: How to create a distribution list in Outlook · How to create rules in Outlook · How to set up email forwarding in Outlook · How to share your Outlook calendar · How to create a task in Outlook

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