smtpprox-loopprevent(1) Transparent SMTP proxy to prevent mail forwarding loops


smtpprox-loopprevent [options] listen.addr:port talk.addr:port


This manual page explains the smtpprox-loopprevent program.

smtpprox-loopprevent is a transparent SMTP proxy which rejects a message message if any of the recipient addresses (Rcpt To:) match a Delivered-To: header.

smtpprox-loopprevent listens on the listen.addr:port address and port and sends smtp traffic unmodified to the SMTP server at talk.addr:port.

smtpprox-loopprevent was written to be a Postfix before-queue content filter, but will function between any SMTP client and server.


The number of child processes to maintain in the service pool. Each child terminates after servicing a random number of messages between minperchild and maxperchild.
[default 16]
Minimum number of messages serviced by a child process.
[default 100]
Maximum number of messages serviced by a child process.
[default 200]
If debugtrace is specified, the prefix will have the PID appended to it for a separate logfile for each child, which will capture all the SMTP dialogues that child services. It looks like a snooper on the client side of the proxy.


Jesse Norell