What is SMTP-Gated ?
It is a server which have the ability to Scan, Recognize, and Block Mails that Containing Spam or Viruses.
How it works ?
It acts like proxy, intercepting outgoing SMTP connections and scanning session data on-the-fly. When messages is infected, the SMTP session is terminated.
- Transparency – is meant to be totally transparent for users, but stone-build for worms 😉
- Message data is intercepted on-the-fly, and scanned just before acknowledged to SMTP server
- Does not break AUTH, PIPELINING or STARTTLS (TLS without scanning)
- Can block messages if AUTH is not used (optionally passing if AUTH is not supported by MSA)
- Can insert source IP (pre-NAT) and ident* into message header
- Can block any mail from infected hosts for defined time
- Logging of MAIL FROM and RCPT TO (plain or as base64-ed MD5)
- Logging of HELO/EHLO hostname
- Can impose some limits on number of SMTP sessions: total, per IP, per ident*
- Can reject connections when load exceeds some limit
- Can skip spam-scanning if load is high
- Executing user script on certain events
- Scanning limited to messages up to configured size
- Can be used to build scanning-farm for one or more routers*
- Logs all connections via syslog
- Has nifty status screen 😉
- Message size limit (since 1.4.16-rc1)
- Outgoing XCLIENT support (since 1.4.16-rc1)
- Conditional content scanning depending on SMTP-AUTH status (since 1.4.16-rc1)
- Regular expression (regex) conditions for HELO/MAIL FROM/RCPT TO (since 1.4.16-rc1)
- SPF checking (since 1.4.16-rc1)
- Content scanning:
- Access checking:
- Uses various NAT frameworks (for standalone mode), or ident/proxy-helper* for external mode