==== Required information ====
- iRedMail version (check /etc/iredmail-release): 0.9.6
- Linux/BSD distribution name and version: Ubuntu 16.04
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): Nginx
- Manage mail accounts with iRedAdmin-Pro?
- Related log if you're reporting an issue:
====

Hello Zhang,
while checking the mail.log file for amavisd startup messages, I noticed that following packlages were missing for proper unpack/check of attachments:

- lrzip
- unzip

I reinstalled them manually via "apt install lrzip unzip"

Maybe these packages can be included in the install script to allow amavis to check and unpack all different attachments.

Cheers,
Bernhard