Blacklist not worked

==== Required information ====
- iRedMail version: 2.1.2
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): LDAP
- Linux/BSD distribution name and version: 6.5
- Related log if you're reporting an issue:
====

We have a spammer which still come even we blacklist the user on the blacklist feature, is any set to blacklist the user ? i input the IP of the sender on iptables too..

Regards,