Preventing external senders from emailing internal Microsoft 365 groups

This recipe provides the necessary steps for preventing external senders from emailing internal Microsoft 365 groups, enhancing control over email communication, and improving security.

Getting ready

Ensure you are an Exchange Administrator or Global Administrator. This task requires the use of the Exchange Online PowerShell module, which should be installed (Install-Module -Name ExchangeOnlineManagement).

How to do it…

1. Use the Connect-ExchangeOnline cmdlet to establish a session (be sure to update it with your own UPN):

   Connect-ExchangeOnline -UserPrincipalName [email protected] -ShowProgress $true

2. Use the Set-UnifiedGroup cmdlet to restrict external senders. Replace GroupName with the name of your Microsoft 365 group:

   Set-UnifiedGroup -Identity "GroupName" -RequireSenderAuthenticationEnabled $true

How it works…

The Set-UnifiedGroup cmdlet configures the properties...