Non-Delivery Report: [501.5.1.8 Your message couldn't be delivered because the email has no mail from address]

Relevant Product: Exclaimer Cloud - Signatures for Office 365

Scenario

You have configured Exclaimer Cloud for your Microsoft 365 tenancy. When you send an email through Exclaimer's server, the email is rejected and you receive a non-delivery report with a similar message:

Please note that the resolution of this issue depends upon different scenarios. There can be instances where:

The email is sent to a group

The email is sent to an individual user

The email was an out of office email

Reason

The error message indicates that the email was sent without a Valid MAILFROM in the message envelope - this means Exclaimer is unable to identify the upstream route for the email and due to this, Exclaimer cannot accept the email into its proxy service.

As per the different scenarios:

• If you receive this error message when the email is sent to a group: This issue occurs when there is no sender specified in the message envelope. If the sender is blank, Signatures for Office 365 cannot identify the tenant to append for the email signature.
  
  
• If you receive this error message when the email is sent to an individual user: According to Microsoft, "Any mail to JournalingReportNdrTo mailbox will not be journaled and it will not honor transport and mailbox rules settings. It is recommended to create a dedicated mailbox for JournalingReportNdrTo setting or set it to an external address."
  
  Note: For more information, see Transport and mailbox rules in Exchange Online or in on-premises Exchange Server don't work as expected.
• If you receive this error message for an out of office email:
  Note: An email message is comprised of headers and body content. When a message is transmitted, the whole thing (headers and body) is wrapped in an envelope. The envelope specifies what system is transmitting the mail, who it is from and who it is being sent to.

  When automatic replies are sent from Microsoft 365, MAIL FROM: information for the envelope is set to <> (that is, there is no MAIL FROM: information). This means that automatic replies trigger an exception in the transport rule that identifies messages to send to Exclaimer Cloud; these messages are not routed to Exclaimer Cloud and therefore, no signature is applied. 

  If the emails with missing MAIL FROM: information cannot be attributed to the correct Microsoft 365 tenant, the delivery will be attempted via an empty sender tenant. Sender Policy Framework (SPF) authentication, as well as other checks, will fail causing the email to be rejected as spam. You will also not be notified of the rejection due to the missing MAIL FROM: information.

Resolution

The resolution of this issue depends on different scenarios, such as:

The email is sent to a group

The email is sent to an individual user

The email was an out of office email

If the email is sent to a group

• If no on-premise Active Directory exists, then amend the distribution group properties in Office 365, using Windows Powershell.
   
  You need to:
  
  Install the Exchange Online PowerShell module
  
  Connect to Exchange Online
  
  Amend distribution group properties

To Install the Exchange Online PowerShell V2 module: 

1. Open the Windows PowerShell and run this command as an Administrator:
   Install-Module -Name ExchangeOnlineManagement
2. Confirm that you want to install this PowerShell module.
   Note: For additional installation options, see ExchangeOnlineManagement.

To connect to Exchange Online: 

• If you have Multi-Factor Authentication enabled, run this command:
  
  Connect-ExchangeOnline -UserPrincipalName <UPN> -ShowProgress $true
  In <UPN> enter your username.
  
  
• If you don't have Multi-Factor Authentication enabled, run this command:
  
  Connect-ExchangeOnline -Credential $UserCredential -ShowProgress $true
  
  When prompted, enter your password (and the Multi-Factor Authentication verification code if required).

To amend the distribution group properties:

1. Run the following command:
   
   Get-DistributionGroup <Group Email Address> | fl *ReportToOriginatorEnabled*
2. If the value returned is False then run this command to change it to True: 
   
   Set-DistributionGroup <Group Email Address> -ReportToOriginatorEnabled $true

• If an on-premise Active Directory exists and the distribution group is synchronized to Office 365, then: 
  
  From the distribution group Properties, set the attribute ReportToOriginator to TRUE.
  
  These changes will not take effect until the on-premises Active Directory domain has been synchronized and replicated in Office 365.
  
  
  Note: For more information, see External recipients don't receive email messages that are sent to a distribution group in Exchange Online, and senders don't receive nondelivery reports.

If the email was sent to an individual user

To resolve this issue, you need to specify a dedicated mailbox, as the recipient for Journal Report NDR messages, in Microsoft 365 using Windows Powershell.

You need to:

Install the Exchange Online PowerShell module  - the steps to install the Exchange Online Powershell module are the same as outlined in If the email is sent to a group section.

Connect to Exchange Online - the steps to connect to Exchange Online are the same as outlined in If the email is sent to a group section.

Specify a dedicated mailbox

To specify a dedicated mailbox:

Run the following command: 

The message was an Out of Office email

To resolve this issue, you need to re-run the setup or upgrade the Transport Rule to prevent Out of Office emails from being sent to Exclaimer Cloud.

You can do one of the following:

• Re-run the Connector Setup wizard: The Office 365 Connector Setup will automatically run the Transport Rule 'Create Bypass Out of Office Transport Rule'. This transport rule will stop all automatic reply emails from being sent to Exclaimer Cloud.
  
  Note: For more information on how to re-run the Setup wizard, see How to re-run the Office 365 Connector Setup Wizard.
  
  
  
• Upgrade your existing subscription: The Upgrade wizard will add a new transport rule in addition to the existing Exclaimer Cloud transport rules already set up. The new rule will ensure that Exclaimer Cloud does not process 'Out of Office' emails. 
  
  Warning: The Upgrade Rule option will not be visible if the new Transport Rule has already been set up via the Setup wizard (if you are a new customer) or if the Upgrade wizard has already been run before.
  For more information on how to setup an Office 365 subscription, see Setup Overview for Office 365.

  
  Upgrading your existing subscription

  To upgrade your existing subscription for the new Transport rule:

  To complete the steps described below, you will need:
  Office 365 Global Administrator credentials
  
  
  1. Log into the Exclaimer Cloud portal, launch your subscription, then click the options list from the top-right of your screen and select Settings: 
     
     
     
     
  2. The Settings window is displayed, select the Mail Flow tab and click Upgrade Rule:
     
     
     
     
  3. You are prompted to sign in (if you haven't already) as a Global Administrator.
     Once you have successfully signed in as a Global Administrator, the Bypass Exclaimer Cloud for Out of Office Messages wizard is displayed:
     
     
     
     
  4. Click Next to proceed. 
     
     
  5. You will be prompted to authorize Exclaimer Cloud to configure Office 365 on your behalf. 
     Copy the code () then click Authorize.  
     
     
      
  6. The Microsoft window is displayed, paste the copied code in the space provided, then click Next:
     
     
     
     The wizard now creates the Out of Office Transport Rule:
     
     
     
     
  7. Once the rule has been successfully created, click Close to complete the setup process: