Message store encryption

==== Required information ====
- iRedMail version (check /etc/iredmail-release):
0.9.2
- Linux/BSD distribution name and version:
Ubuntu 14.04 LTS
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):
MySQL
- Web server (Apache or Nginx):
Apche
- Manage mail accounts with iRedAdmin-Pro?
No
- Related log if you're reporting an issue:
====

Is there any way to encrypt the message store (/vmail/domain.com) ?