Does Exclaimer support Message Recall

Scenario

You would like to know if Exclaimer supports the Message Recall feature in Microsoft Outlook.

Resolution

Yes, Exclaimer supports the use of the Message Recall feature; however, there are some limitations you should be aware of:

• Message recall uses a Messaging Application Programming Interface (MAPI) property named SearchKey, to correctly identify the message in the recipient's mailbox.
  
  Microsoft Exchange uses the SearchKey property for multiple purposes; however, a connector-routed email is likely to change this property. If an email is routed via a connector, then the message recall is unlikely to succeed, as it cannot determine the correct message to be recalled.
  
  Exclaimer has confirmed with Microsoft that they cannot alter this behavior. As Exclaimer and many other vendors' Server-Side solutions use connectors, we recommend using Client-Side signatures in organizations where the message recall feature is essential.
  
  To maximize your chances of message recall functioning where emails are sent via connectors:
  
  
  • Check if 'TNEFenabled' is set to 'true' or not for the 'default' Remote Domain. If it is not 'true', we recommend setting 'TNEFenabled' for the internal domains. For further information, please see Transport Neutral Encapsulation Format (TNEF).
    
    
  • Create two Transport rules, one to stop recall messages routing through Exclaimer and the other to stop the Microsoft 365 Message Recall reports routing through Exclaimer.
    
    Select an option below to view the related instructions:
    
    Option 1: Run PowerShell script to stop recall messages from being routed through Exclaimer
    To run the PowerShell script to stop recall messages from being routed through Exclaimer:
    

    1. Open Windows PowerShell as an Administrator.
    
    2. Run:

    set-executionpolicy unrestricted

    3. To download the script, run:

    Invoke-WebRequest -URI https: https://raw.githubusercontent.com/exclaimerltd/Internal-Support-Scripts/master/messageRecallFix.ps1

    $ScriptPath = "$env:LOCALAPPDATA\temp\messageRecallFix.ps1"

    Invoke-Expression $ScriptPath

    4. Navigate to the directory where the script has been saved:
    cd "C:\Users\ReplaceWithUserName\Downloads
    
    4. Run the script: 

    \MessageRecallFix.ps1
    Option 2: Manually create Transport Rules to stop recall messages from being routed through Exclaimer

    To manually create Transport rules to stop recall messages from being routed through Exclaimer:
    1. Open the Exchange admin center.
    
    

    2. From the menu sidebar, select Mail flow, then select Rules.
    
    3. Create Transport Rule 1.
    
    For Transport Rule 1, set the following rule conditions:
    
    Apply this rule if
    'x-ms-exchange-recallreportgenerated' header contains ''true' or 'false''
    
    Do the following
    set message header 'X-ExclaimerHostedSignatures-MessageProcessed' with the value 'true'.
    
    
    _{Rule description for Transport rule 2.}
    4. Create Transport Rule 2.
    
    For Transport Rule 2, set the following rule conditions:
    
    Apply this rule if
    'X-MS-Exchange-Generated-Message-Source' header contains ''Transport Message Recall Routing Agent''
    
    Do the following
    set message header 'X-ExclaimerHostedSignatures-MessageProcessed' with the value 'true'.
    
    
    _{Rule description for Transport rule 2.}
    
    5. Make sure both Transport Rules have higher priority (low priority number) as compared to the Identify messages to send to Exclaimer Cloud rule. 
    
    
    _{Make sure both Transport Rules have higher priority (low priority number) as compared to the Identify messages to send to Exclaimer Cloud rule.}

• Message recall requires both the sender and the recipient to have a Microsoft 365 or Microsoft Exchange email account in the same organization. This means that the recall message will not work if you send emails externally, for example, to your customers or personal email accounts like Gmail, Yahoo and so on.
  
  
• If the recipient has already read the email message, the recall will not work as intended. In this case, the recipient will be notified that the sender wanted to recall the message.
  
  
• Both the recall message and the email to be recalled must exist in the same folder in the recipient's mailbox.

• You cannot recall a message that's protected by Azure Information Protection.

For more information, see Microsoft's documentation on message recall.