How do I set up a 2nd work email with a different domain name than my business account

Dear @Gwen Dougherty, 

Good day, and I appreciate the clear explanation of your concern. I understand that you currently have a Microsoft 365 business account and would like to use a second work email address with a different domain name. This is absolutely supported in Microsoft 365 and I am happy to outline the available options so you can choose what best fits your needs. 

Before using any email address on a new domain, that domain must first be added and verified in your Microsoft 365 tenant by an administrator. Once that is complete, there are several ways to proceed, depending on whether you want the email to use the same inbox or a separate one. 

Option 1: Use one inbox and add the second address as an alias 

This option is best if you want all email to arrive in the same mailbox and you want the ability to send from the second address. No additional license is required. 

Sign in to the Microsoft 365 admin center as an administrator. 

Go to Settings, then Domains, and select Add domain. 

Add the new domain and verify ownership by completing the required DNS records at your domain registrar. 

After the domain is verified, go to Users, then Active users, and select your user account. 

Choose Manage username and email, then add a new alias using the new domain. 

Note: Aliases share the same inbox, calendar and storage. Replies sent from the alias will only work after the send from alias setting is enabled and has finished propagating. 

Add a custom domain to Microsoft 365 - Microsoft 365 admin | Microsoft Learn 

Connect your domain by adding DNS records - Microsoft 365 admin | Microsoft Learn 

Option 2: Create a separate mailbox using the second domain 

This option is best if you want a fully independent inbox, calendar, rules, and storage. This option requires an additional Microsoft 365 license. 

Ensure the new domain has already been added and verified in the Microsoft 365 admin center. 

Go to Users, then Active users, and create a new user account. 

Choose the new domain for the user’s email address. 

Assign a Microsoft 365 license that includes Exchange Online, such as Business Standard, E3, or E5. 

After provisioning completes, sign in to Outlook or add the new mailbox as an additional account in Outlook. 

Note: Each licensed mailbox is billed separately and functions independently from your existing account. 

Option 3: Create a shared mailbox on the new domain 

This option is ideal for role based or team addresses such as info@ or sales@ and doesn't require a license up to 50 GB. 

Confirm the new domain is verified in the Microsoft 365 admin center. 

Go to Teams and groups, then Shared mailboxes, and create a new shared mailbox using the new domain. 

Assign members who should have access to the mailbox. 

Grant Send as or Send on behalf permissions as needed. 

Note: Shared mailboxes don't have their own sign-in. Users access them through their existing accounts. 

About shared mailboxes in Microsoft 365 - Microsoft 365 admin | Microsoft Learn 

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To have a second work email that uses a different domain than the existing business account in Microsoft 365, the high-level steps are:

1. Decide whether the new email is in the same tenant or a separate one
   • Same Microsoft 365 tenant: Add the new domain to the existing Microsoft 365 subscription and create a mailbox/user that uses that domain.
   • Separate tenant: Sign up for a separate Microsoft 365 subscription and set it up with the new domain.
2. If using the existing Microsoft 365 tenant: add the new custom domain
   1. Sign in to the Microsoft 365 admin center as an admin.
   2. Go to Settings > Domains.
   3. Select Add domain.
   4. Follow the steps to confirm ownership of the domain (via your domain host) and let Microsoft 365 guide through adding the required DNS records so the domain is connected and can be used for email.
3. Create or update a user to use the new domain
   • After the domain is added and configured:
     1. In the admin center, go to Users > Active users.
     2. Either create a new user or edit an existing one.
     3. Change the user’s sign-in name/email address so that the part after @ uses the new domain (for example, change ******@oldbusiness.com to ******@newdomain.com).
   • When this is done, that user will have a mailbox on the new domain.
4. If using a separate Microsoft 365 subscription for the new domain
   1. Sign up for a new Microsoft 365 for business subscription (for example, Business Standard or Business Basic) and choose to use a new or existing domain during sign-up.
   2. If using an existing domain, follow the steps in Add a custom domain to Microsoft 365 to connect that domain and add DNS records.
   3. Add users and assign licenses in that new tenant so they get mailboxes on the new domain.
5. Configure Outlook to use both work accounts
   • On a computer:
     1. Open Outlook.
     2. Go to File > Info > Add Account.
     3. Enter the email address for the second work account and complete sign-in.
   • On mobile (for example, Outlook for Android):
     1. Open Outlook.
     2. Open the menu, go to Settings.
     3. Select Add Account, then add the second work email account.

After these steps, there will be two separate work email addresses, each using its own domain, and both can be accessed in Outlook or other supported clients.

References:

• Set up Microsoft 365 Business Standard with a new or existing domain
• Change your Microsoft 365 email address to use your custom domain
• Set up Microsoft 365 Business Basic
• Add a custom domain name
• Set up email in the Outlook for Android app
• Use a screen reader to set up your email account in Outlook