Add a shared mailbox to Outlook

Create a shared mailbox, give people access, open it in Outlook, send from it and use its calendar.

Who this is for: Microsoft 365 administrators who create shared mailboxes and give people access, and the people who then use the mailbox in Outlook.

A shared mailbox lets a group of people read and answer email sent to one address, such as [email protected]. Replies appear to come from the shared mailbox, not from the person who sent them. Every shared mailbox also has a shared calendar.

This guide covers Microsoft 365 with Exchange Online, classic Outlook and new Outlook for Windows, and Outlook on the web. It does not cover a hybrid Exchange organisation, where shared mailboxes are created in the on-premises Exchange admin centre, and it does not cover Outlook for Mac or the Outlook mobile apps.

Before you start

Your subscription must include email (Exchange Online). Microsoft 365 Business Standard includes it; Microsoft 365 Apps for business does not.
To create a shared mailbox and give access you need the Exchange admin role. If the admin centre says "You don't have permission to access this page or perform this action", ask someone with that role.
Everyone who uses the shared mailbox needs their own licensed Exchange Online mailbox. The shared mailbox itself needs no licence while it holds up to 50 GB.
The shared mailbox needs an Exchange Online Plan 2 licence if it will hold more than 50 GB (the limit then rises to 100 GB) or be placed on litigation hold. A larger archive needs Exchange Online Plan 2, or Exchange Online Plan 1 with the Exchange Online Archiving add-on.
Only people inside your organisation can use a shared mailbox, and it supports at most 25 users. For more people, or for people outside your organisation, use a Microsoft 365 group instead.

Create the shared mailbox

Sign in to the Microsoft 365 admin centre with an account that has the Exchange admin role.
Go to Teams & Groups > Shared mailboxes. If you do not see Teams & Groups, select Show all in the left navigation pane.
Select + Add a shared mailbox and enter a name, for example Info. The email address is filled in from the name; change it if you need a different address.
Select Save changes. It can take a few minutes before you can add members.
Under Next steps, select Add members to this mailbox.
Select Add members, select the people who will use the mailbox, select Add and close the pane.
Check that the new mailbox is listed on the Shared mailboxes page.

Important A new shared mailbox has sign-in blocked. Keep it blocked: nobody signs in to a shared mailbox directly. Its account has a system-generated password that nobody knows or should use. People open the mailbox from their own account, as described below.

Check or change who has access

Two permissions make a shared mailbox work: Full Access lets a person open the mailbox and read, change and delete its mail and calendar, and Send As lets them send email that looks as if the shared mailbox sent it. Full Access alone does not let anyone send from the mailbox. Check or change both here:

In the Exchange admin centre, go to Recipients > Mailboxes.
Select the shared mailbox, then select Edit.
Under Mailbox permissions, select Manage mailbox delegation.
To give Full Access or Send As, select Add next to that permission and select the people. To take it away, select Remove.
Select Save. The people you added see the change in the permission list.

Note Give the permissions to people directly, not to a security group. Outlook adds the mailbox automatically only for people who hold the permission themselves.

Important Removing someone's Full Access takes the mailbox away from them, and anyone with Full Access can delete its messages: there is no setting that stops them. If deletions must be prevented, use a Microsoft 365 group instead.

Add the shared mailbox in Outlook

Once a person has access, Outlook usually adds the mailbox for them. Newly given access can take a few minutes to appear.

Classic Outlook for Windows

Close and restart Outlook. The shared mailbox appears in the Folder Pane. If it does not, wait a few minutes and restart Outlook again. If it still does not appear, add it yourself:

Select File > Account Settings > Account Settings.
On the Email tab, select your account and select Change.
Select More Settings > Advanced > Add.
Type the shared mailbox address, for example [email protected].
Select OK > OK, then Next > Finish > Close. The shared mailbox is now listed in the Folder Pane.

New Outlook for Windows

Close and restart new Outlook; the mailbox appears in the Folder Pane. If it does not, wait a few minutes and restart again. To add it yourself:

Select Mail in the navigation pane.
In the Folder Pane, right-click your account name and select Add shared folder or mailbox.
Type the shared mailbox address and confirm.
Expand the Shared with me folder: the shared mailbox is listed there.

Outlook on the web

In the left navigation pane, right-click Folders and select Add shared folder or mailbox.
Enter the shared mailbox address and confirm. The mailbox appears in your folder list.

To get notifications of new messages, open the mailbox in its own window instead: select your name, select Open another mailbox and enter the address.

Send email from the shared mailbox

Classic Outlook: select New Email. If you do not see From, select Options > From. Select the shared address, or select Other email address, type it and select OK.
New Outlook: select New > Mail. If you do not see From, go to the Options tab and select Show From. Choose the shared address under From, or select Other email address and type it. After the first time, it stays in the list.
Outlook on the web: select New mail, then More actions > Show From. The first time, right-click the address in From, select Remove and type the shared address.

Recipients see only the shared address. You need Send As (see above) for this to work.

Use the shared calendar

In Outlook, go to the calendar view. In classic Outlook the shared calendar is added to your Calendars list after you restart Outlook.
Select the shared mailbox's calendar.
Create, view or change appointments as you would in your own calendar. Every member of the shared mailbox sees the changes.

When it goes wrong

Problem	Likely cause	What to do
The shared mailbox does not appear in Outlook.	Access was given a few minutes ago, or it was given to a security group, so Outlook does not add it automatically.	Wait a few minutes and restart Outlook. If it still is not there, give the permission to the person directly, or add the mailbox yourself as described above.
"This message could not be sent. You do not have the permission to send the message on behalf of the specified user."	The new mailbox, or the new member, has not yet reached every Microsoft data centre.	Wait an hour and send again. If it still fails, check that the person has Send As.
Sending as the shared mailbox fails in classic Outlook.	The mailbox is hidden from the address list (HiddenFromAddressListsEnabled is True).	An administrator runs `Set-Mailbox -Identity [email protected] -HiddenFromAddressListsEnabled $false` in Exchange Online PowerShell, then the person restarts Outlook.
The mailbox receives email but nothing can be sent from it, and later senders get a non-delivery report.	It has reached its 50 GB limit.	Delete or archive old mail, or assign it an Exchange Online Plan 2 licence: in the admin centre go to Users > Active users, select the shared mailbox, open the Licenses and Apps tab, tick the licence and select Save changes.
Creating it fails with "The proxy address ... is already being used".	Another mailbox already uses that name.	Create the mailbox with a different name, then rename it on the Shared mailboxes page.