«An SMTP Filtering Proxy»
The Big Picture
smtpf sits in front of one or more MTAs
on SMTP port 25. It acts as a
proxy, filtering and forwarding mail to one
or more MTAs, which can be on the same machine or different machines.
By using an independent SMTP pre-filter in the form of a proxy we avoid portability differences
and limitations of MTA extension methods (milters, plugins, rule sets, etc.) and tighly couple
& integrate tests to improve performance & message throughput.
smtpf supports a variety of well blended anti-spam filtering techniques that can be individually enabled or
disabled according to the rigours of the postmaster's local filtering policy. Some of the tests available are:
- Avast!, ClamAV, and F-Prot anti-virus support
- "Client-Is-MX" heuristics for PTR and IP in name checks
- Concurrent connection limits
- Connection rate throttling
- DNS real-time black, grey, and white lists
- Enhanced grey-listing
- HELO claims to be us
- Local black/white list by IP, host name, domain, MAIL, RCPT
- Message limit & size controls
- Recipient verification using call-ahead
- Sender verification using call-back
- SIQ protocol support for reputation services
- SMTP command & greet pause
- SpamAssassin anti-spam support
- SPF Classic support
- Tar pitting negative SMTP responses
- URI blacklist test of PTR, HELO, and MAIL
- URI blacklist testing of message content
- White wash & backscatter prevention with EMEW
Another feature of smtpf is the multicast / unicast cache, which provides a
fast, simple, and efficient means to share cache updates across multiple machines on the
same network segment or to a set of remote hosts. The multicast / unicast cache use
a broadcast-and-correct model and support IPv4 & IPv6.
Copyright 2006, 2013 by SnertSoft. All rights reserved.
BarricadeMX trademark & patents pending.
dastardly villians since 1 November 2006