SMTP Security Servers

[yogi_ccse]

Can anyone please send me how SMTP security Server Works.
I've read on CP docs but no good info.
I've configured 2 rules as follows:-

Sr. No. Source Destination Service Action
1. Any MailServer smtp->antiSpoof resource Drop
2. any MailServer smtp->Valid resource Allow

the purpose of 1. is to drop spoofed emails originating from certain source. so we match only sender and nothing else is configured

the purpose of second is to allow legitimate mails recd by our mail server, we 've used smtp resources for this. in 2. smtp resource we've specified IP of our mail server ,nothing else. it works perfect.,
ISSUE: some spoofed emails still gets into the mail server, i suspect SMTP security server is not able to handle big load, hence it is missing some mails.

any idea?
:)
thx
Yogi

[wowtek]

Any details about antiSpoof resource ?