Set-UnifiedGroup Alias -PrimarySmtpAddress ‘Alias’ is the mailbox alias, and should match what you typed into the ‘Group email address’ field. You can adjust the email address with a PowerShell command afterwards as per the Microsoft Support article: If you create an Office 365 Group this way, it won’t show for Outlook 2016 users in a hybrid setup. When you create an Office 365 Group through the Office 365 Admin Center (which is now renamed to the Microsoft 365 Admin Center), the domain for the email address has a drop down arrow, but is greyed out so can’t actually be changed – it will only show you the default domain: Many people configure their primary email domain the same as the UPN, which is then the same as their default Office 365 domain. Update – The above is also true if your autodiscover record points to your on-premises Exchange server, so if you have no on-premises mailboxes, change that to. However, as covered in this Microsoft Support article, when using a hybrid setup between Exchange on-premises and Exchange Online, Office 365 Groups won’t show in Outlook when the email address of the group is anything but (with ‘contoso’ being your Office 365 tenant name). The user doesn’t have to do anything, they just show up. Normally, any Office 365 Group a user is a member of, will show at the bottom of their mailbox folders under a section called ‘Groups’. If you’re running Exchange in hybrid mode, there’s a big gotcha with Office 365 Groups and the ability to display them in Outlook 2016.

Office 365 outlook icons disappered