Sorry about that, but Im going crazy with this problem. Here goes again.

==== Required information ====
- iRedMail version (check /etc/iredmail-release): 0.9
- Linux/BSD distribution name and version: Ubuntu 14.04
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): PGSQL
- Web server (Apache or Nginx): Apache
- Manage mail accounts with iRedAdmin-Pro? NO
- Related log if you're reporting an issue:

I've migrated a VM with Iredmail and now it doesnt start. It seems like a problem with the permits of /va/lib/postfix but i've changed it and it doesn't works.
This is mail.log:
Jul  8 09:22:14 areasmail2 postfix/postqueue[2191]: fatal: Queue report unavailable - mail system is down
Jul  8 09:22:44 areasmail2 postfix/master[2342]: fatal: open lock file /var/lib/postfix/master.lock: cannot open file: Permission denied

and this are the permisions of the folders /var/lib/postfix
total 136
drwxr-xr-x  2 clamav postfix   4096 Jul  8 09:07 .
drwxr-xr-x 44 root   root      4096 Apr 21 11:05 ..
-rwxr-xr-x  1 clamav postfix     33 Jun  5 11:14 master.lock
-rwxr-xr-x  1 clamav postfix   1024 Jul  7 15:36 prng_exch
-rwxr-xr-x  1 clamav postfix 114688 Jul  7 16:05 smtpd_scache.db
-rwxr-xr-x  1 clamav postfix   8192 Jun  5 11:31 smtp_scache.db

Thanks for the help Zhang. The problem was bigger than that. When I moved the VM I don't know why but the permission on the postfix queues messed up. I had to change the ownership of all the queues on /var/spool/postfix/.

Thanks for the help.