Strange and curious problem with spam

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

I've discovered a little strange and curious problem.
If you are rebooting the server and at the same time you are receiving spam email, tha spam email become double: one go to quarantine correctly and another copy arrive at destination mailbox tagged with ***SPAM*** in subject.
It's there a way to not deliver the spam email to the final recipient?

Thank you