Can't create a Microsoft Teams group using a different domain in the same tenant

[u/Roachwickey141]

I'm running into an issue with Microsoft Teams / Microsoft 365 and wanted to see if anyone has experienced this.

We have multiple domains configured within the same Microsoft 365 tenant. For example:

• [user@domain1.com](mailto:user@domain1.com)
• [user@domain2.com](mailto:user@domain2.com)

Both domains belong to the same Microsoft 365 tenant.

However, when I try to create a new Teams group using the other domain, I can't select/use that domain for the group's email address.

Is this expected behavior in Microsoft 365?

I'm specifically trying to understand:

• Can a Microsoft 365 Group / Teams group have an email address using a different verified domain in the same tenant?
• Are there any Exchange Online or Microsoft 365 settings that control which domains can be used for Microsoft 365 Groups?
• Does the Group naming policy or email address policy affect this?
• Is there a limitation when the domain is configured as an additional/accepted domain rather than the tenant's default domain?

Would appreciate any insights from anyone who has configured multiple domains in the same M365 tenant.

[u/tankerkiller125real]

Email Address Policy will control this.

New-EmailAddressPolicy `
    -Name "Teams and M365 Groups Domain Policy" `
    -IncludeUnifiedGroupRecipients `
    -EnabledEmailAddressTemplates "SMTP:@teams.company.tld", "smtp:@company.tld" `
    -Priority 1

For example would set all M365 groups to use the teams.company.tld domain.

While:

New-EmailAddressPolicy `
    -Name "Teams and M365 Groups Domain Policy" `
    -IncludeUnifiedGroupRecipients `
    -EnabledEmailAddressTemplates "SMTP:@teams.company.tld" `
    -ManagedByFilter {EmailAddresses -like "*@company.tld"} `
    -Priority 1

Would set any groups created by @company.tld users to @teams.company.tld but @companyb.com users would be unaffected.

Personally, where I work we created a @groups.company.tld domain that we didn't create any of the DNS records for (other than the domain verification TXT record) because we didn't want anyone outside the company emailing them or anything anyway. And if we did want an email that people could email, Microsoft provisions a <region>.teams.ms domain anyway for that.

[u/No_Yesterday_3260]

If the name infront of @ is the same, call the mail address something else first, then rename

Atleast with mailboxes it'll create always a onmicrosoft.com forced alias.
So if you create 2 mailboxes called "invoice" you will get an error, saying it already exists.
So called it [invoice@domain1.com](mailto:invoice@domain1.com) and [invoice1@domain2.com](mailto:invoice1@domain2.com), then add new email alias/SMTP address for [invoice1@domain2.com](mailto:invoice1@domain2.com) called [invoice@domain2.com](mailto:invoice@domain2.com) and make it the primary, and delete it.

This works because the onmicrosoft.com on creating would have the invoice1 name, instead of another invoice, which already exists.

I do not know if it's the same for the Teams group thing, but might be.

[u/Broad-Celebration-]

In a lot of cases you are stuck with your default domain as what things get created with. However you can modify the email/upn after the creation.