---
name: "smtpprox-loopprevent"
section: "1"
platform: "linux"
package: "smtpprox-loopprevent"
version: "0.1-1"
release: "Debian 10 (Buster)"
platforms: ["linux"]
url: "https://new.carta.tech/smtpprox-loopprevent"
---

# smtpprox-loopprevent(1)

Transparent SMTP proxy to prevent mail forwarding loops

## NAME

smtpprox-loopprevent - Transparent SMTP proxy to prevent mail forwarding loops

## SYNOPSIS

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

## DESCRIPTION

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.

## OPTIONS

- \--children=N

  **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*.\
   \[default 16\]

- \--minperchild=N

  **Minimum number of messages serviced by a child process.**\
   \[default 100\]

- \--maxperchild=N

  **Maximum number of messages serviced by a child process.**\
   \[default 200\]

- \--debugtrace=filename\_prefix

  **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.

## SEE ALSO

[*smtpprox*(1)](/smtpprox/1.md)  *http://www.postfix.org/SMTPD\_PROXY\_README.html*

## AUTHOR

Jesse Norell