smtp-gated

Homepage: http://smtp-proxy.klolik.org/
Supports: clamd
smtp-gated is a transparent SMTP proxy supporting: NAT on Linux (netfilter), NAT on FreeBSD (ipfw and others getsockopt-compatible), or dedicated mode (separate/external machine). DATA traffic is spooled in write-thru mode and then scanned for viruses or spam. The program is transparent for TLS connections.