Messages sent to distribution groups do not have a signature applied

Relevant Products: Exclaimer Cloud - Signatures for Office 365

Scenario

When an email message is addressed to a distribution group (either in the 'To:' or 'CC:' fields) the sender's email signature is not added to the received message. At the same time, the Return-Path header on the received message is blank and only contains anchor tags.

Cause

The problem occurs because there is no sender specified on the message envelope. When the sender is blank, Signatures for Office 365 cannot identify the tenant to append an email signature.

Resolution

If the group is synchronized to Office 365 from an on-premise Active Directory, set the attribute ReportToOriginator to TRUE in the properties of the distribution group in the on-premise Active Directory site.

These changes will not take effect until the on-premises Active Directory domain has been synchronized and replicated in Office 365.

Further information relating to this can be found in the following Microsoft KB article.

If no on-premise Active Directory exists, the group properties can be amended in Office 365 using Windows Powershell.

1. Open Windows PowerShell and run the following PowerShell command to create a variable which will gather logon credentials:

   $credential = (get-credential)

   When you press Enter, you are prompted to enter Office 365 administrator credentials.
2. Run the following Powershell command:
   

   Import-PSSession (New-PSSession -ConfigurationName Microsoft.Exchange -Credential $Credential -ConnectionURI https://ps.outlook.com/powershell -Authentication Basic -AllowRedirection) -AllowClobber

3. Run the following Powershell command:
   

   Get-DistributionGroup <Group Email Address> | fl *ReportToOriginatorEnabled*

4. If the value returned is False, run the command below to change it to True:
   

   Set-DistributionGroup <Group Email Address> -ReportToOriginatorEnabled $true