Add or remove an email alias in Microsoft 365

An email alias is an extra address that delivers to an existing Microsoft 365 mailbox, such as jen@yourbusiness.co.uk arriving in Jenna's inbox. This guide shows you how to add an alias, how to remove one (including from a shared mailbox), and how to fix the "already being used as an alias" error.

• Applies to: Microsoft 365 Business Basic, Standard and Premium
• Time: about 5 minutes
• Difficulty: Beginner

Before you start

• You need an admin account with the Global Administrator or Exchange Administrator role. See Give someone admin rights.
• The domain you want to use (for example yourbusiness.co.uk) must already be added and verified in Microsoft 365. See Connect your domain to Microsoft 365.
• Aliases are free. Each user can have up to 400 of them, and they don't need an extra licence.

Add an alias to a user

1. Sign in to the Microsoft 365 admin centre. Go to admin.microsoft.com and sign in with your admin account.
2. Open the user. Select Users → Active users, then click the person's name to open their details pane.
3. Choose Manage username and email. On the Account tab, under Aliases, select Manage username and email. This option only appears if the user has a licence assigned.
4. Add the alias. Type the part before the @ in the Username box, pick your domain from the drop-down list, then select Add.
5. Save. Select Save changes. New aliases usually work within an hour, but Microsoft allows up to 24 hours.

Remove an alias from a user

1. Open the user. In the admin centre go to Users → Active users and select the person who has the alias. If you don't know who has it, type the address into the search box at the top of the admin centre.
2. Choose Manage username and email. On the Account tab, select Manage username and email.
3. Delete the alias. Find the address in the Aliases list and select the bin icon next to it.
4. Save. Select Save changes. The address is now free to use on another user, group or shared mailbox (allow up to an hour for this to take effect).

Add or remove an alias on a shared mailbox

Shared mailboxes are managed in the Exchange admin centre rather than under Active users.

1. Open the Exchange admin centre. Go to admin.exchange.microsoft.com (or, in the Microsoft 365 admin centre, select Show all → Exchange).
2. Find the mailbox. Select Recipients → Mailboxes, then click the shared mailbox. User and shared mailboxes appear in the same list.
3. Manage its addresses. On the General tab, under Email addresses, select Manage email address types.
4. Add or remove. To add, select Add email address type, choose SMTP, type the new address and confirm. To remove, select the bin icon next to the address you no longer want.
5. Save. Select Save and close the pane.

The same Manage email address types screen works for any mailbox, so you can also use it for user mailboxes if you prefer.

Troubleshooting

"This email address is already being used as an alias for user..."

Every address in Microsoft 365 must be unique. Someone else (a user, shared mailbox or group) already has it. Search for the address in the admin centre to find who owns it, remove it there using the steps above, wait a few minutes and try again.

I can't see Manage username and email

The user has no licence assigned. Either assign one (see Add a user and assign a licence) or manage their addresses from the Exchange admin centre instead.

My domain isn't in the drop-down list

The domain hasn't finished verifying in Microsoft 365. Check Settings → Domains in the admin centre. If it shows as incomplete, follow Connect your domain to Microsoft 365.

Mail to the new alias bounces

Give it time, up to 24 hours on a new tenant or domain. If it still bounces, check the domain's MX record points to Microsoft 365. See Microsoft 365 DNS records on Host Dada nameservers.

Last reviewed: October 2026