How to Create a Shared Mailbox in Microsoft 365

Set up a shared address such as support@, add members, and check the permissions needed to read and reply to mail.

When a shared mailbox fits

A shared mailbox lets several people monitor a common address and use its calendar. It works well for a support or reception inbox where staff should reply under the team address. It differs from a Microsoft 365 group, and Microsoft says a shared mailbox cannot be migrated directly to a group. In a hybrid Exchange environment, follow your organization’s on-premises Exchange procedure instead.

Create the mailbox

1. Sign in to the Microsoft 365 admin center with an account holding the Exchange admin role.
2. Open Teams & Groups → Shared mailboxes. Select Show all if the section is hidden.
3. Select Add a shared mailbox. Enter a display name and review the suggested email address.
4. Select Save changes. It may take a few minutes before member management becomes available.
5. Under Next steps, choose Add members to this mailbox and add the employees who need access.

Check sending permissions

Full Access lets a person open and manage messages and calendar entries, but does not by itself let them send from the mailbox. Send As makes a reply appear to come from the shared address. Send on Behalf identifies the employee as sending on behalf of that address. Review mailbox delegation in the Exchange admin center, grant only the permissions the team needs, and test receipt and reply from a member’s own account.

Keep the mailbox manageable

Direct sign-in to a new shared mailbox is blocked by default; members should use their own accounts. Outlook may add the mailbox automatically after a restart when permissions are assigned directly. Shared mailboxes usually do not need their own license, but Microsoft lists scenarios requiring Exchange Online Plan 2, including more than 50 GB of storage, in-place archiving, or Litigation Hold. Assign someone to oversee the inbox so messages are not missed or answered twice.

Sources

Microsoft Learn: Create a shared mailbox; Microsoft Learn: About shared mailboxes.