'\" t
.\"<!-- Copyright 2013 Double Precision, Inc.  See COPYING for -->
.\"<!-- distribution information. -->
.\"     Title: ratefilter
.\"    Author: Sam Varshavchik
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 10/28/2020
.\"    Manual: Double Precision, Inc.
.\"    Source: Courier Mail Server
.\"  Language: English
.\"
.TH "RATEFILTER" "8" "10/28/2020" "Courier Mail Server" "Double Precision, Inc."
.\" -----------------------------------------------------------------
.\" * Define some portability stuff
.\" -----------------------------------------------------------------
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.\" http://bugs.debian.org/507673
.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.ie \n(.g .ds Aq \(aq
.el       .ds Aq '
.\" -----------------------------------------------------------------
.\" * set default formatting
.\" -----------------------------------------------------------------
.\" disable hyphenation
.nh
.\" disable justification (adjust text to left margin only)
.ad l
.\" -----------------------------------------------------------------
.\" * MAIN CONTENT STARTS HERE *
.\" -----------------------------------------------------------------
.SH "NAME"
ratefilter \- Rate\-limiting mail filter
.SH "SYNOPSIS"
.HP \w'\fBfilterctl\fR\ 'u
\fBfilterctl\fR {[start] | [stop]} ratefilter
.SH "DESCRIPTION"
.PP
Enable this filter to enforce a maximum number of messages accepted from the same sender\&.
.PP
\fBratefilter\fR
uses the following configuration files\&. Changes to the following files do not take effect until the filter has been stopped and restarted\&.
.PP
/etc/courier/filters/ratefilter\-interval
.RS 4
This file contains a single numerical value that sets the rate limiting time interval setting, in seconds\&. The default value is sixty seconds\&. Sixty seconds is also the minimum acceptable interval\&.
.RE
.PP
/etc/courier/filters/ratefilter\-maxrcpts
.RS 4
This file contains a single numerical value that sets how many receipients the same sender can send mail to, within the controlling time interval\&. The default value is 100 recipients\&.
.RE
.PP
/etc/courier/filters/ratefilter\-minuid
.RS 4
When
\fBratefilter\fR
is enabled for locally originating mail, this sets the minimum system userid that has rate limiting enforced\&. The default value is 100\&. Mail sent by processes with lower uids are not subject to rate limiting\&.
.RE
.PP
/etc/courier/filters/ratefilter\-mode
.RS 4
If this file exists and contains the word "all",
\fBratefilter\fR
creates its listening socket in
/var/lib/courier/allfilters, otherwise the socket gets created in
/var/lib/courier/filters, see
\m[blue]\fB\fBcourierfilter\fR(8)\fR\m[]\&\s-2\u[1]\d\s+2
for more information\&.
.RE
.PP
The
enablefiltering
settings controls whether local or
ESMTP
mail is subject to rate limiting, see
\m[blue]\fB\fBcourier\fR(8)\fR\m[]\&\s-2\u[2]\d\s+2
for more information\&.
.PP
In this context,
\(lqlocal\(rq
mail refers to mail that gets sent when a process executes the
\m[blue]\fB\fBsendmail\fR(1)\fR\m[]\&\s-2\u[3]\d\s+2
command\&. This does not include mail sent via connection to local port 25, this is considered
ESMTP
mail\&.
.PP
Local mail gets rate limited based on the sending process\*(Aqs userid\&. Each numerical userid gets treated as an individual sender\&.
ESMTP
mail\*(Aqs sender is taken from the authenticated
ESMTP\*(Aqs userid\&. Non\-authenticated
ESMTP
mail is not subject to rate limiting\&.
.PP
Rate limiting is implemented by dividing chronological time into intervals that are half the time interval given in the
ratefilter\-interval
setting\&. For example, with the default interval of sixty seconds, chronological time gets divided into thirty second intervals\&.
.PP
\fBratefilter\fR
counts the number of receipients in each message (and not just the number of messages) from each sender, in each time interval\&.
.PP
\fBratefilter\fR
rejects the message when the total number of recipients from all messages from the same sender in the current and the previous time interval exceeds the
ratefilter\-maxrcpts
setting\&. The rejected message\*(Aqs number of recipients also get counted, for the purpose of rejecting future messages\&.
.SH "SEE ALSO"
.PP
\m[blue]\fB\fBcourierfilter\fR(8)\fR\m[]\&\s-2\u[1]\d\s+2\&.
.SH "AUTHOR"
.PP
\fBSam Varshavchik\fR
.RS 4
Author
.RE
.SH "NOTES"
.IP " 1." 4
\fBcourierfilter\fR(8)
.RS 4
\%http://www.courier-mta.org/courierfilter.html
.RE
.IP " 2." 4
\fBcourier\fR(8)
.RS 4
\%http://www.courier-mta.org/courier.html
.RE
.IP " 3." 4
\fBsendmail\fR(1)
.RS 4
\%http://www.courier-mta.org/sendmail.html
.RE