Shared Mailbox

A shared mailbox is an Exchange Online mailbox that multiple users can read and send from, without a Microsoft 365 licence per user (up to 50 GB; beyond that, a licence is required). Users can't sign into a shared mailbox directly — they're delegated access via Full Access and Send As or Send on Behalf permissions, after which the mailbox appears as a separate folder tree in their Outlook. Used for team addresses like support@, sales@, or info@, where many people need to see incoming mail and respond from the shared identity. Mail to a shared mailbox does not fan out — it lands once in the shared inbox.