Bypass greylisting

==== Required information ====
- iRedMail version: 0.8.4
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Linux/BSD distribution name and version: Debian/Squeeze
- Related log if you're reporting an issue:
====

Hello,

Is it possible for me to bypass greylisting for a list of trusted email senders ? Thus I will receive those trusted emails instantaneously.

Thanks.