Administration - Google Workspace - Graymail Prefix

This article contains information on configuring a message prefix in Google Workspace Admin Console to help users identify and filter possible spam or graymail messages by creating client-side rules.

Prerequisites

• You are a Google Workspace Admin Console administrator.

Overview

Microsoft Outlook / Outlook 365 allows you to create server-side rules for Graymail, e.g. to look for “X-Mimecast-Bulk-Signature: yes” within a message header and move it to a user’s Graymail folder. See Mimecast for Outlook - Graymail Rule

By comparison, Google Workspace does not allow server-side rules, and can only filter client-side based on user-visible fields; basic header and message body (i.e. not complete header information). 

The steps in this article give an alternative solution, utlizing Google Workspace Admin Console to add a message prefix to possible spam / graymail, so that End Users can create client-side filters.

Configuring a Message Prefix in Google Workspace

You can configure a message prefix in Google Workspace, by using the following steps:

1. Log in to Google Workspace Admin Console.
2. Navigate to Gmail | Content Compliance.
   
    
3. Set up a Mimecast Graymail rule for Inbound messages:
   • Select the Inbound checkbox.
     
      
   • Add Content value of “X-Mimecast-Bulk-Signature: yes”.
     
      
   • Under Modify Message, check Add X-Gm-Spam and X-Gm-Phishy headers.
     Enter the required message prefix under Prepend custom subject, e.g. "[POSSIBLE SPAM]".
      
   • Ensure Bypass spam filter for this message is unchecked.
   • Click on Save.
4. End Users will now see possible Graymail messages prefixed as per the Prepend custom subject.
5. End Users can create a message rule, to move messages containing the Prepend custom subject phrase to a specified folder.

See Also...

• Mimecast for Outlook - Graymail Rule