A shared mailbox lets several people read and reply to one address, such as info@, sales@ or a leaver's old mailbox, and it doesn't need a paid licence. This guide shows you how to convert an existing user mailbox to a shared mailbox (keeping all its email and calendar), how to create a new one, and how to remove the licence afterwards so you stop paying for it.
Before you start
- You need an admin account with the Global Administrator or Exchange Administrator role (see Give someone admin rights).
- To convert a user mailbox, the user must still have a licence assigned. If you've already removed it, add it back first, otherwise the convert option won't appear.
- Don't delete the user account before converting. The shared mailbox lives on that account.
Shared mailbox facts worth knowing
| Question | Answer |
|---|---|
| Does it need a licence? | No, as long as it holds 50 GB or less and doesn't use archiving or litigation hold. |
| What if it's bigger than 50 GB? | Either delete large old messages to bring it under 50 GB, or assign an Exchange Online Plan 2 licence (raises the limit to 100 GB). |
| Can people sign in to it directly? | New shared mailboxes have sign-in blocked. A converted mailbox keeps its old password, so reset the password or block sign-in afterwards. |
| Does it have a calendar? | Yes. Every member can see and edit the shared calendar. |
| Who sees replies? | Replies sent from the shared mailbox appear to come from the shared address, not the person who wrote them. |
Convert a user mailbox to a shared mailbox
This is the usual route when someone leaves and you want to keep their email accessible. All existing email, calendar items and inbox rules are kept.
- Sign in to the Microsoft 365 admin centre. Go to admin.microsoft.com.
- Open the user. Select Users → Active users and click the person's name.
- Convert the mailbox. On the Mail tab, select Convert to shared mailbox, then Convert. It takes a minute or two.
- Secure the account. The old username and password still work after conversion. On the same user, select Reset password (and, for a leaver, Block sign-in) so the former user can't get back in. See Remove a leaver for the full checklist.
- Remove the licence. If the mailbox is under 50 GB, open the user again, go to the Licenses and apps tab, untick the Microsoft 365 licence and select Save changes. The user now shows as Unlicensed.
- Add members. Follow "Give people access" below so the right people can open it.
If you've already deleted the user
Restore the user from Users → Deleted users (possible for 30 days after deletion), assign a licence, reset the password, wait for the mailbox to reappear (up to 24 hours), then convert it as above and remove the licence.
Create a new shared mailbox
- Open Shared mailboxes. In the admin centre select Teams & groups → Shared mailboxes. If you can't see Teams & groups, select Show all in the left menu first.
- Add the mailbox. Select Add a shared mailbox. Enter a display name such as
Sales. The email address fills in automatically; change it if needed and make sure your own domain is selected, not the onmicrosoft.com one. - Save. Select Save changes. Wait a few minutes before adding members.
Give people access
- Open the mailbox. In Teams & groups → Shared mailboxes, select the mailbox (converted mailboxes appear here too).
- Add members. In the details pane, find Members and choose to edit them (on a brand-new mailbox, use Add members to this mailbox under Next steps). Select Add members, choose the people and select Add. Members get permission to read the mailbox and send as it.
- Wait for Outlook to pick it up. In Outlook for Windows the mailbox usually appears in the folder list by itself after the user closes and reopens Outlook (this can take up to an hour). In Outlook on the web, mobile and Mac, the user adds it themselves. See Microsoft's guides linked below.
Room and equipment mailboxes
If what you need is a bookable meeting room, pool car or projector, use a resource mailbox instead. Like shared mailboxes they're free, and they accept or decline meeting invites automatically. Create them in the Exchange admin centre under Recipients → Resources, then invite the room to meetings like any other attendee. See Microsoft: Manage resource mailboxes.
Troubleshooting
There's no "Convert to shared mailbox" option
The user has no licence. Assign one on the Licenses and apps tab, wait a few minutes, then try again.
The shared mailbox doesn't appear in Outlook
Ask the user to close and reopen Outlook and give it up to an hour. If you gave access through a security group rather than to named people, it won't appear automatically; add the people individually instead. On a phone, add it from the Outlook app's account settings.
"Shared mailbox is over its size limit" or mail bouncing
Without a licence the limit is 50 GB. Delete or archive large messages, or assign an Exchange Online Plan 2 licence. Ask us if you need one added to your subscription.
Replies show my name instead of the shared address
In Outlook, make sure the From field shows the shared mailbox address before sending. If it's missing, show the From field in the message options and pick or type the shared address.
Last reviewed: October 2026
