Discover and Learn the Endless Tech Innovations

Mailfront Plugin Rblcheck

  • Table of Content
  • Introduction
  • Environment Configuration
  • Sender Action
  • Recipient Action
  • Data Action
  • Message Action
  • Requirements
  • Installation
  • Mailfront Plugins Configuration
  • License
  • Changes
  • Download


Last Updated: 29 Jan 2010 GMT +8.

This plugin provides an ability for rejecting/deferring/tagging messages based on $RBLCHECK environment variable. $RBLCHECK is set by patched rblsmtpd if the sender's IP is listed.

IMPORTANT: This plugin is written for and tested with mailfront 1.12 and should work with later version.

Environment Configuration

If set, messages will be rejected with code 554.
If set, messages will be deferred with code 451.
Do not set this environment variable as this is set by using patched rblsmtpd. You need to patch ucspi-tcp-0.88/rblsmtpd.c with the combined patch (ucspi-tcp-0.88-rblsmtpd.c-combined.patch) provided in this package.

Sender Action


Recipient Action


Data Action

When client starts to transmit data, this plugin will start its checking for $RBLCHECK environment variable. If $RBLCHECK is not empty, the message will be rejected or deferred or tagged.

If $RBLCHECK_REJECT is set, message will be rejected with code 554.

If $RBLCHECK_DEFER is set, message will be deferred with code 451.

If $RBLCHECK_REJECT and $RBLCHECK_DEFER not set, the following line will be added to the message header:

X-RBL-Check: rbl1 rbl2 rbl3

If you run rblsmtpd -l -l -l -l -l -l -l -l, rblsmtpd set the $RBLCHECK environment variable with means the sender's IP is listed at and RBL database:


Note: If sender is authenticated or $RELAYCLIENT environment variable is set, then this plugin will be skipped.

Message Action



  • mailfront version 1.12 or later
  • bglibs version 1.104 or later (might work with earlier version)
  • patch ucspi-tcp-0.88 with ucspi-tcp-0.88-rblsmtpd.c-combined.patch provided


  • Build and install mailfront
  • Switch back to this package
  • Adjust the contents of the conf-* files
  • Build the sources by running "make"
  • Install the plugin by running "make install"

Mailfront Plugins Configuration

Place rblcheck in mailfront's plugin list. Depending on your setup:

  • edit the smtpfront-qmail shell script and place the string rblcheck after add-received
  • edit the PLUGINS environment variable and place the string rblcheck after add-received
  • place the argument rblcheck after the add-received of the mailfront command

Set up environment as described in Environment Configuration above or plugin-rblcheck.html which is included in the package.


This package is copyright © 2010 Giam Teck Choon or CHOON.NET, and may be copied according to the GNU GENERAL PUBLIC LICENSE (GPL) Version 2 or a later version. A copy of this license is included with this package. This package comes with no warranty of any kind.


  • 29 Jan 2010 GMT +8 : version 0.01
  • Initial release