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How Many Domains and Email Aliases Can Microsoft 365 Support?

Elise Williams Oct 23, 2026 868 views

Question details

The user wants to know the maximum number of domains and email aliases supported by Microsoft 365 for both business and personal accounts.

How Many Domains and Email Aliases Can Microsoft 365 Support?

Product: Microsoft 365
Device & OS: not provided
Scenario: Planning or managing email infrastructure and multiple domain addresses within a Microsoft ecosystem.
Observed behavior: Needing to configure multiple domains or aliases to send and receive emails from different addresses under a single tenant or account.

Before you start

Determine whether you are using a Microsoft 365 Business subscription or a personal Microsoft account, as the administration interfaces and alias limits differ significantly.

Solution 1Recommended

Managing Domains and Aliases in Microsoft 365 Business

Business tenants offer extensive support for multiple domains and aliases through the Microsoft 365 admin center.

Microsoft 365 Business tenants allow you to add up to 900 domains per subscription. Each user mailbox can have up to 400 email aliases. Sending from an alias requires specific permissions configured by the administrator.

Add and verify domains

Go to the Microsoft 365 admin center and navigate to 'Settings' > 'Domains' to add and verify your custom domains.

Select a user

Go to 'Users' > 'Active users' and select the user mailbox where you want to add aliases.

Add the alias

Under the 'Account' tab, select 'Manage username and email' to add the new alias using your verified domains.

Enable sending permissions

To allow sending from an alias, ensure the 'Send from aliases' setting is enabled in the Exchange admin center.

Managing Domains and Aliases in Microsoft 365 Business

Sending vs Receiving: By default, aliases are only for receiving emails. To send from an alias, the admin must explicitly grant send-as permissions.

Solution 2

Managing Aliases for Personal Microsoft Accounts

Personal accounts have stricter limits on alias creation and management compared to business tenants.

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Frequently Asked Questions

Can I send an email from my Microsoft 365 alias?

Yes, in Microsoft 365 Business, you can send emails from an alias if your administrator has enabled the 'Send from aliases' setting in the Exchange admin center and granted you the necessary permissions.

Will creating an alias affect my original email address?

No, adding an alias simply adds another email address that delivers to your existing inbox. You will receive mail sent to both the alias and your original address in the same place.

Can I set up a rule to handle emails sent to my alias differently?

Yes, you can create inbox rules to move or categorize messages sent to a specific alias, though these rules generally do not apply to emails automatically flagged as junk.

What happens if I delete an alias on my personal Microsoft account?

If you delete an alias on a personal account, it opens up one of your 10 available alias slots. However, Microsoft limits you to creating a maximum of 10 new aliases per year, regardless of deletions.

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