problem with psd match

[afshin lamei]

Hi all,
I'm using the psd (port scan detector) , dropping all packets that
match with psd and it works well with default values. but when I use
the retina port scanner, it says that ports 25 (smtp) and 110 (pop3)
are open. I have not any mail application and my box is not listening
on these ports (netstat -an --inet proves this). all default policies
(iptables -P ) are set to DROP.
what's the problem?
regards
afshin lamei