How to Add a Shared Mailbox in Outlook

What Is a Shared Mailbox in Microsoft 365?

A shared mailbox is a mailbox that multiple people can use to read and send email from a common address—like info@yourcompany.com or support@yourcompany.com. Unlike regular user mailboxes, shared mailboxes don't require a separate license or password. Team members access them through their own Outlook accounts, and any replies they send appear to come from the shared address rather than their personal email.

Shared mailboxes are ideal for customer service teams, general inquiries, departments that need a unified inbox, or any scenario where more than one person needs visibility into the same stream of email.

Shared Mailbox vs. Distribution List vs. Microsoft 365 Group

How to Create a Shared Mailbox (Admin Steps)

Before anyone on your team can add a shared mailbox to Outlook, an admin needs to create it and assign members. Here's how.

Option 1: Microsoft 365 Admin Center

1. Sign in to the Microsoft 365 admin center at admin.microsoft.com.
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") and an email address (e.g., support@yourcompany.com).
5. Click Save changes. It may take a few minutes to provision.
6. Under Next steps, click Add members to this mailbox.
7. Select the users who need access and click Add.

Important: Members receive both Full Access (can read and manage mail) and Send As (can send email as the shared address) permissions by default. You can adjust these in the Exchange admin center if needed.

Option 2: Exchange Admin Center

1. Go to the Exchange admin center at admin.exchange.microsoft.com.
2. Navigate to Recipients > Mailboxes.
3. Click Add a shared mailbox.
4. Fill in the display name and email address, then click Create.
5. Once created, select the mailbox and go to Delegation to add members with Full Access and Send As permissions.

Option 3: PowerShell

For admins who prefer the command line, you can create a shared mailbox and assign permissions in a few commands:

PowerShell Commands:
New-Mailbox -Shared -Name "Customer Support" -DisplayName "Customer Support" -Alias support

Add-MailboxPermission -Identity "Customer Support" -User "john@yourcompany.com" -AccessRights FullAccess -InheritanceType All

Add-RecipientPermission -Identity "Customer Support" -Trustee "john@yourcompany.com" -AccessRights SendAs -Confirm:$false

Note: You need to be connected to Exchange Online PowerShell first. If you haven't set that up, see our guide on how to connect to Exchange Online PowerShell.

How to Add a Shared Mailbox in Outlook (Desktop)

Once your admin has added you as a member, the shared mailbox should appear automatically in your Outlook folder pane. If it doesn't, here's how to add it manually.

New Outlook for Windows

1. Close and reopen Outlook. The shared mailbox should appear automatically in your folder pane.
2. If it doesn't, right-click your account name in the left sidebar.
3. Select Add shared folder or mailbox.
4. Type the name or email address of the shared mailbox (e.g., support@yourcompany.com).
5. Click Add. The shared mailbox will appear in your folder list.

Classic Outlook for Windows

1. Open Outlook and go to File > Account Settings > Account Settings.
2. On the Email tab, select your account and click Change.
3. Click More Settings > Advanced tab.
4. Click Add under "Open these additional mailboxes."
5. Type the name of the shared mailbox and click OK through all dialogs.
6. The shared mailbox will appear in your folder pane after Outlook refreshes.

Outlook for Mac

1. If you've been added as a member, the shared mailbox should appear automatically after restarting Outlook.
2. If it doesn't, go to Tools > Accounts.
3. Select your Exchange account and click Delegation and Sharing.
4. Under Shared with me, click + and search for the shared mailbox.
5. Select it and click Add.

How to Add a Shared Mailbox in Outlook on the Web

Outlook on the web offers two ways to access a shared mailbox.

Method 1: Add It to Your Folder Pane (Recommended)

This lets you monitor both your personal inbox and the shared mailbox at the same time.

1. Sign in to outlook.office.com.
2. In the left navigation, right-click Folders.
3. Select Add shared folder or mailbox.
4. Type the name or email address of the shared mailbox and click Add.
5. The shared mailbox will appear below your personal folders.

Method 2: Open in a Separate Window

If you prefer to keep the shared mailbox in its own browser tab:

1. Click your profile icon in the top-right corner.
2. Select Open another mailbox.
3. Type the email address of the shared mailbox and press Enter.
4. The shared mailbox opens in a new browser window.

How to Add a Shared Mailbox in Outlook Mobile

The Outlook mobile app for iOS and Android supports shared mailboxes natively.

1. Open the Outlook app on your phone.
2. Tap your profile icon in the top-left corner.
3. Tap the gear icon (Settings).
4. Under Mail accounts, tap Add mail account.
5. Select Add a shared mailbox.
6. Type the email address of the shared mailbox and tap Add.
7. The shared mailbox will appear as a separate account in your Outlook app.

Note: You'll need to be added as a member by your admin before the mailbox will load on mobile. If you get an error, confirm your permissions with your IT team.

How to Send Email from a Shared Mailbox

Once you've added the shared mailbox, sending email from it is straightforward—but the steps vary slightly depending on which version of Outlook you're using.

In Outlook Desktop (New and Classic)

1. Click New Email.
2. Click Options > From (or look for the From field at the top of the message).
3. Select the shared mailbox address from the dropdown. If it doesn't appear, click Other email address and type the shared address manually.
4. Compose your message and click Send.

The recipient will see the email as coming from the shared mailbox, not your personal address. Outlook remembers this choice, so the shared address will be available in the From dropdown for future messages.

In Outlook on the Web

1. Click New mail.
2. At the top of the message, click the three dots (...) and select Show From.
3. Click From and type the shared mailbox address.
4. Compose and send.

In Outlook Mobile

1. Switch to the shared mailbox account by tapping your profile icon.
2. Tap the compose button.
3. The email will automatically send from the shared address.

Troubleshooting Common Issues

Shared mailboxes are generally reliable, but here are the most common problems and how to fix them.

The shared mailbox doesn't appear in Outlook

• Wait 15–60 minutes after being added as a member. Permissions can take time to propagate.
• Restart Outlook completely (close and reopen, don't just minimize).
• Add it manually using the steps above for your version of Outlook.
• Check with your admin to confirm you have Full Access permissions.

You can't send as the shared mailbox

• You need Send As or Send on Behalf permission in addition to Full Access.
• Ask your admin to verify your Send As delegation in the Exchange admin center or via PowerShell.
• If you see "sent on behalf of" in the From field instead of just the shared address, you have Send on Behalf permission rather than Send As. Your admin can update this.

Shared mailbox not syncing on mobile

• Remove and re-add the shared mailbox in Outlook mobile settings.
• Make sure the Outlook app is updated to the latest version.
• Confirm that your admin hasn't restricted mobile access to the shared mailbox.

Auto-mapping isn't working

• Auto-mapping only works when Full Access is assigned directly to a user—not through a security group.
• If permissions were assigned via a group, you'll need to add the mailbox manually.
• Your admin can disable auto-mapping and re-enable it via PowerShell if it gets stuck.

Shared Mailbox Best Practices

• Set clear naming conventions — Use addresses that describe the function, like support@, info@, or billing@.
• Limit the number of members — Too many users on one shared mailbox creates noise. Keep it to the people who actually need access.
• Use folders and rules — Set up inbox rules to auto-sort incoming mail by category, client, or priority.
• Monitor the mailbox regularly — Shared mailboxes don't send notifications by default. Assign someone to check it or set up flow rules to notify the team.
• Watch the 50 GB limit — Shared mailboxes are free up to 50 GB. Beyond that, you'll need to assign an Exchange Online license. Archive old mail to stay under the limit.
• Use "Send As" over "Send on Behalf" — For a cleaner customer experience, Send As makes it look like the email came directly from the shared address.

Common Questions About Shared Mailboxes in Outlook

Does a shared mailbox need a Microsoft 365 license?

No. Shared mailboxes are free and don't require a separate license as long as they stay under 50 GB. If you need more storage or features like auto-expanding archives, you'll need to assign an Exchange Online Plan 1 or Plan 2 license.

Can I access a shared mailbox from my phone?

Yes. The Outlook mobile app for iOS and Android natively supports shared mailboxes. Add it through Settings > Add mail account > Add a shared mailbox.

What's the difference between "Send As" and "Send on Behalf"?

Send As makes the email appear to come directly from the shared mailbox—the recipient has no idea who actually wrote it. Send on Behalf shows the recipient something like "John Smith on behalf of Customer Support." For most teams, Send As provides a cleaner experience.

Can I set up automatic replies on a shared mailbox?

Yes. An admin can configure automatic replies through the Exchange admin center, or any member with Full Access can set them up through Outlook on the web by opening the shared mailbox and going to Settings > Automatic replies.

How many people can access a shared mailbox?

Microsoft doesn't enforce a hard limit on the number of members, but performance degrades beyond 25 users. For larger teams, consider a Microsoft 365 Group or a ticketing system instead.

Take Control of Your Team's Email

Shared mailboxes are one of the simplest and most underused tools in Microsoft 365. Setting one up takes minutes, costs nothing, and gives your team a unified way to manage email without stepping on each other's toes.

If your organization needs help configuring shared mailboxes, managing permissions, or optimizing your Microsoft 365 environment, Always Beyond's team of IT specialists can handle the setup—so you can focus on running your business.