Creating a shared mailbox is useful for multiple people to to monitor and send email from a common address. When a person in the group replies to a message sent to the shared mailbox, the email appears to be from the shared mailbox, not from the individual user. For example, "firstname.lastname@example.org" would be an example of a shared mailbox.
Create a shared mailbox and add members
- Sign in with a global admin account or Exchange admin account. If you get the message "You don't have permission to access this page or perform this action," then you aren't an admin.
- In the admin center, go to the Groups > Shared mailboxes page.
On the Shared mailboxes page, select + Add a mailbox. Enter a name for the shared mailbox. Then the wizard chooses the email address, but you can edit it.
4. Select Add. It may take a few minutes before you can add members.
5. Under Next steps, select Add members to this mailbox. Members are the people who will be able to view the incoming mail to this shared mailbox, and the outgoing replies.
6. Select the +Add members button. Put a check mark next to the people who you want to use this shared mailbox, and select Save.
7. Select Close.
You now have created the Shared Mailbox, which includes a shared calendar as well.
Block sign-in for the shared mailbox account
Every shared mailbox has a corresponding user account. Notice how you weren't asked to provide a password when you created the shared mailbox? The account has a password, but it's system-generated (unknown). You aren't supposed to use the account to log in to the shared mailbox.
But what if an admin simply resets the password of the shared mailbox user account? Or what if an attacker gains access to the shared mailbox account credentials? This would allow the user account to log in to the shared mailbox and send email. To prevent this, you need to block sign-in for the account that's associated with the shared mailbox.
- In the admin center, go to the Users > Active users page.
- In the list of user accounts, find the account for the shared mailbox (for example, change the filter to Unlicensed users).
- Select the user to open their properties pane, and then select the Block this user icon .
Note: If the account is already blocked, Sign in blocked will appear at the top and the icon will read Unblock this user.
4. In the Block this user? pane, select Block the user from signing in, and then select Save changes.