I saw an interesting Reddit thread from someone who was confused about the difference between Microsoft account aliases and separate accounts.
The user had opened the Microsoft account page for managing account names. At the bottom of that page, they saw the option to "Add email" and then choose “Create a new email address and add it as a username.”
They thought this would create a separate but linked Microsoft account. In reality, it adds a new alias to the existing account.
Can an alias become a separate Microsoft account?
No. An address that is added to a Microsoft account as an alias cannot be moved to another account later. If you remove that address from the account, it is permanently retired and cannot be reused by anyone.
The same principle applies in reverse: separate Microsoft accounts cannot be merged into one account.
How aliases work
An alias is an alternate email address for the same mailbox. Messages sent to the alias arrive in your existing inbox, and replies are sent from the address the message was sent to.
You can make aliases easier to manage by using rules. For example, you can:
- Move messages sent to a specific alias into a dedicated folder.
- Apply a category so you can quickly identify which address received the message.
Why use aliases?
Aliases are useful for many of the same reasons people use multiple mailboxes: they help limit who has your main address and make spam easier to manage.
For example, you can use an alias when signing up for websites. If that address starts receiving too much spam, you can delete the alias or use a rule to move those messages to a folder.
If you only use aliases for website sign-ups, consider disabling sign-in for those addresses. Then, if a site database is compromised, the exposed address cannot be used to sign in to your Microsoft account.
Alias limits
Microsoft limits how many aliases you can create and keep on an account:
- You can have up to 10 addresses on one Microsoft account.
- You can create only one new alias every two weeks.
- You can create no more than 10 aliases per year.
For example, if you add one alias per month for nine months and then delete one, you may need to wait until the oldest alias is a year old before you can add a replacement.
Sending mail from an alias
Aliases work especially well for incoming mail and replies. Replies are sent from the address that received the original message.
Sending a new message from an alias takes a little more attention. You need to choose the alias in the From field, and the display name is the same for all aliases on the account.
Changing the From address works in Outlook apps. Many other mail apps send only from the primary address. If you have not disabled sign-in for the alias, you may be able to configure the account in another mail app using that alias and a different display name.
Changing the default sending address
If you use Outlook on the web, you can change the default sending address for new messages by going to File > Settings > Mail > Forwarding and IMAP.
This setting applies only to Outlook on the web. It does not change the default sending address in other Outlook apps.
Changing the primary alias
If you want a different address to be the primary address for the account, make that change in your Microsoft account settings.
Be careful not to remove an address unless you are certain you no longer need it. Removed Microsoft aliases cannot be recovered. Microsoft also limits primary alias changes to once every two weeks.
When a separate account may be better
A second account can be useful when you need to send mail from a different address and want to keep that identity separate for privacy reasons.
However, I would not use a second Microsoft account as the recovery account for the first one. Too many people end up locked out of both accounts, or they forget to use the second account and it is eventually deleted.
Keep inactive accounts from being closed
If you do not sign in to an account regularly, Microsoft can purge the mailbox after one year and delete the account after two years.
The exception is an account with an active Microsoft 365 subscription. In that case, mailbox purging and account deletion are paused while the subscription remains active. When the subscription ends, the inactivity clock starts again.
My recommendation
I prefer aliases over multiple accounts because they are easier to manage and help simplify email use. They also let me use different addresses when signing in to websites, which helps protect my main account from attackers.
If you truly need a second account, consider using a different email service, such as Gmail or Yahoo. For two-step verification and recovery, it is often best to use accounts from two different services. Just make sure you sign in to every email account at least once a year so the account is not closed for inactivity.
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