Steps to fix RAR file scanning with Amavisd
Mails with .rar files are tagged as UNCHECKED mail.
There is an issue with the Amavis code where unrar package is installed and amavisd is not able to check .rar attachments and adding UNCHECKED at the subject line. This issue is fixed in latest Amavisd version, and you can see .rar file handling details in official release-notes of Amavisd.
Since ZCS v8.6 was built with amavisd-new-2.9.0 and due to amavisd bug all previous versions having this issue. Where ZCS v8.7 shipped with latest Amavisd v2.10.1 and now .rar attachments are scanning without any problems.
By default package managers (Yum, apt) installs latest unrar version 5.x. To prevent this issue on ZCS v8.6 and older versions we need to install unrar v4.x, because amavisd-new-2.9.0 is not working properly with unrar v5.0.x
To see complete description about Amavisd and rar file handling visit following bugzilla links:-