Antispam settings in CommunigatePro

Protect local groups

Protect local groups against external mass senders: the groups can be mailed only locally.This will be a cluster-wide rule. Go to Settings/Mail/Rules andadd new "local groups" rule with priority 9.Priority should be higher than that of the virus scan rule to avoid scanningmessages that will be rejected anyway. Set rule properties:

Note1. Trusted sources are machines from one of local networks<. Authenticated sources provide user/password credentials when session is started.
 
Note2. Giving this rule higher priority than the antispam rule<, the latter is not invoked on mass spam mailings saving CPU
 
 
Note3. To troubleshoot this rule, temporarily exclude some host from local networks by adding its IP address prefixed by exclamation sign, e.g.
	10.20.0.0-10.20.255.255
!10.20.2.1<
at the end of LAN IPs list. For details to appear in CGP log for this particular machine, add its IP to the Debugging IPs list.

Other antispam settings

  • Settings/General/Other: Hide 'Account Unknown' messages = Yes
  • Settings/Mail/SMTP/Receiving - protect against brute-force password attacks:
    • Limits / Non-client Sender / Delay Prompt for = 3 sec
    • Processing / Verify / Check SPF records = Enabled
  • Settings/Mail/RFCReader/Banned Header Lines - block RFC reader:
From: *<*|*@*>
From: *|*
Return-Path: *<|*@*>
Return-Path: *|*<
  • Domain Defaults/Unknown Names:
    • Consult External Authenticator for Unknown = No
    • Mail to Unknown = Rejected
    • Calls to Unknown = Rejected
    • Access to Unknown = Rejected
  • Access to Domain settings / All @ domain:
    • Mail to All is distributed for = nobody
    • Mail to All is sent to Forwarders = No