Messages sent to SharePoint or Office 365 groups generate an NDR

Scenario:

When using Exclaimer Cloud - Signatures for Office 365, messages sent to SharePoint or Office 365 groups are not delivered and the sender receives a Non Delivery Report (NDR).

Cause:

This issue occurs because the sender is not authenticated and so the message is not sent.

Resolution:

As a workaround, sender authentication can be disabled via PowerShell.

1. Run PowerShell (as an administrator).
2. Run the following command and enter Office 365 Administrator credentials:
   

   $UserCredential = Get-Credential

3. Connect to Office 365:
   

   $Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell-liveid/ -Credential $UserCredential -Authentication Basic -AllowRedirection    

4. Run the following command:
   

   Import-PSSession $Session

5. To obtain a list of SharePoint groups, run the following command:
   

   Get-UnifiedGroup

6. Locate the required group and note the Group Name.
7. Run the following command, replacing GroupName with the name of the group identified in the previous step:

   Set-UnifiedGroup -identity GroupName -RequireSenderAuthenticationEnabled $False