O365 Admin
How to Set Up a Shared Mailbox in Microsoft 365
Published 25 November 2025
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6 min read
Shared mailboxes let multiple users send and receive email from a shared address like info@contoso.com without a separate licence. This guide covers creating shared mailboxes, granting access, and managing them via PowerShell.
Create a shared mailbox
Microsoft 365 admin centre → Teams & groups → Shared mailboxes → + Add a shared mailbox
Enter the display name and email address, save, then add members. Shared mailboxes do not require a licence for the mailbox itself.
Grant access permissions
Connect-ExchangeOnline # Full Access (read and manage) Add-MailboxPermission -Identity "helpdesk@contoso.com" -User "sarah@contoso.com" -AccessRights FullAccess -AutoMapping $true # Send As (from address shows helpdesk@) Add-RecipientPermission -Identity "helpdesk@contoso.com" -Trustee "sarah@contoso.com" -AccessRights SendAs
Permission types
Full Access
Read, move, delete email in shared mailboxSend AsMost common choice
From address shows shared mailbox addressSend on Behalf
Shows "User on behalf of Shared Mailbox"Convert a user mailbox to shared
# Convert departing user mailbox to shared - preserves email without a licence Set-Mailbox -Identity "leaver@contoso.com" -Type Shared
Frequently Asked Questions
Q: Do shared mailboxes need a licence?
No licence required up to 50GB. Users who access it need their own Exchange Online licence.
Q: Can a shared mailbox sign in directly?
By default shared mailboxes are blocked from direct sign-in. Only grant access via Full Access/Send As permissions.
Q: How do I set an out-of-office for a shared mailbox?
Use PowerShell: Set-MailboxAutoReplyConfiguration -Identity "helpdesk@contoso.com" -AutoReplyState Enabled -InternalMessage "..." -ExternalMessage "..."