The document describes troubleshooting an issue where emails were being deferred from a Zimbra mail server due to port 10024 being refused. The potential causes were a failed or stopped amavisd service, an out-of-date ClamAV antivirus package, or a stale amavisd.pid file. The resolutions included restarting the amavisd service, upgrading ClamAV, and removing and updating the amavisd.pid file before restarting Zimbra services.