How to track a message sent to a mailing list

Introduction

Sometimes users send messages to mailing lists, and the message gets "lost."  This article discusses how to find out what happened to the message.  

Procedure

1. Access the server's command line as the 'root' user via SSH or "Terminal" in WHM.
2. Find the message in the Exim log.

   grep for.*list@mydomain.tld /var/log/exim_mainlog | grep sender@somedomain.tld | tail

   Please note that "list@mydomain.tld" and "sender@somedomain.tld" must be replaced with the mailing list's address and the message sender's address.
3. Locate the message's id value from the output.

   id=1598252431.j70vPATnUD9yOPtF@mailserver.test

4. Find the message in the mailman logs.

   grep 1598252431.j70vPATnUD9yOPtF\@mailserver.test /usr/local/cpanel/3rdparty/mailman/logs/*

   Please note that message IDs can contain special characters you may need to escape with a backslash (\) character to search the logs for them.  
5. Check the returned log(s) for more information.