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ratefilter(8)


NAME

   ratefilter - Rate-limiting mail filter

SYNOPSIS

   filterctl {[start] | [stop]} ratefilter

DESCRIPTION

   Enable this filter to enforce a maximum number of messages accepted
   from the same sender.

   ratefilter uses the following configuration files. Changes to the
   following files do not take effect until the filter has been stopped
   and restarted.

   /etc/courier/filters/ratefilter-interval
       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.

   /etc/courier/filters/ratefilter-maxrcpts
       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.

   /etc/courier/filters/ratefilter-minuid
       When ratefilter 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.

   /etc/courier/filters/ratefilter-mode
       If this file exists and contains the word "all", ratefilter creates
       its listening socket in /var/lib/courier/allfilters, otherwise the
       socket gets created in /var/lib/courier/filters, see
       courierfilter(8)[1] for more information.

   The enablefiltering settings controls whether local or ESMTP mail is
   subject to rate limiting, see courier(8)[2] for more information.

   In this context, "local" mail refers to mail that gets sent when a
   process executes the sendmail(1)[3] command. This does not include mail
   sent via connection to local port 25, this is considered ESMTP mail.

   Local mail gets rate limited based on the sending process's userid.
   Each numerical userid gets treated as an individual sender.  ESMTP
   mail's sender is taken from the authenticated ESMTP's userid.
   Non-authenticated ESMTP mail is not subject to rate limiting.

   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.

   ratefilter counts the number of receipients in each message (and not
   just the number of messages) from each sender, in each time interval.

   ratefilter 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's number of recipients also get counted, for the purpose of
   rejecting future messages.

SEE ALSO

   courierfilter(8)[1].

AUTHOR

   Sam Varshavchik
       Author

NOTES

    1. courierfilter(8)
       [set $man.base.url.for.relative.links]/courierfilter.html

    2. courier(8)
       [set $man.base.url.for.relative.links]/courier.html

    3. sendmail(1)
       [set $man.base.url.for.relative.links]/sendmail.html



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