eliminate-dups [options] [dbname]
dbname is not specified, it defaults to
Reads an email message on standard input and calculates a fingerprint based on the mail headers. If the fingerprint already exists in the hash file, then the message is a duplicate. If the fingerprint does not exist, save the fingerprint in the hash file and deliver the message.
The following command-line options are supported:
Dump the fingerprint DB human-readably and exit. Implies
Print a usage message and exit
Do not compute any message fingerprints (i.e., only purge). The same exit status will be returned as if a fingerprint check found no match--i.e., any message on standard input will not be flagged as a duplicate.
Do not purge the fingerprint DB (i.e., only check). This option can be used to reduce load on the mail server. The script should periodically be run with the
--no-check option to keep the fingerprint database from growing without limit.
Include the message body when calculating fingerprints.
Contradictory options are silently accepted. For example,
--no-check is inconsistent with
--strict, but no error is reported if both are used. Similarly,
--no-purge together mean that the script does nothing (unless
--help is also specified), but this doesn't result in an error.
Create a ~/.qmail-maildir file
Then add the following lines to your ~/.qmail file
| eliminate-dups hashfile &user-maildir
Forwarding to the user-maildir address is very important. It ensures that if delivery to the Maildir is deferred, eliminate-dups will not be called a second time (which would result in a lost message).
To reduce server load, the following can be used in the ~/.qmail file instead:
| eliminate-dups --no-purge hashfile &user-maildir
--no-purge option is used, then a cron job must be set up to purge the fingerprint database periodically. The following can be put in the user's crontab file:
23 2 * * * /path/to/eliminate-dups --no-check $HOME/.maildups
Copyright (C) 2007-2008 Len Budney
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.