Amavis does not parse exe in rar archive

==== Required information ====
- iRedMail version:
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):
- Web server (Apache or Nginx):
- Linux/BSD distribution name and version:
- Related log if you're reporting an issue:
======== Required information ====
- iRedMail version: 0.9.0
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):LDAP
- Web server (Apache or Nginx):Apache
- Linux/BSD distribution name and version:ubuntu 14.04
- Related log if you're reporting an issue:
====

Good morning,

if I send or I receice an email with attachment, for example an exe inside a zip or tar.gz archive , amavis  bann them .

but it doesn't work with rar archive with an exe file inside.

i've installed unrar-free, and when i start amavis as a service it finds rar encoder.

it seems amavis doesn't recognize rar archive.

how can I resolve this?

thanks

regards