vulneravility relaying mail through our iredmail server

==== Required information ====
- iRedMail version: 0.8.6
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): LDAP
- Linux/BSD distribution name and version: CentOS release 6.4 (Final)
- Related log if you're reporting an issue:
====

Hello, i have thousands mail using our server for relaying spam mail. I have no account on security password compromise.

Need top now what the way for determinate what package ( s ) have vulnerabilities and how to correct the problem.

For now i haved to stop postfix, for stop send span mail.

Need to now what other info is needed for determinate what the problem is

Urgent.

Thanks in advance