This is a minimal language to filter mails using maildrop and perl. You write the filter rules in a plain text file, use the perl script in this repository to convert the filter rules to a maildrop script, and configure your mail server to use the maildrop script.
For example this will move all mails about Subject test to testfolder:
Subject: test
=> testfolder
This will move all mails that are either about Subject test or from someone@example.org to testfolder:
Subject: test
From: someone@example.org
=> testfolder
Regular expressions can be used to match the values:
Subject: /test[0-9]+/
From: /someone@example\.(org|com)/
=> testfolder
As well as to match the entire header line (in this form they are passed unchanged to maildrop):
/Subject:\s*test[0-9]+$/
/From:\s*someone@example.(org|com)/
=> testfolder
Blocks surrounded by {} are also passed unchanged to maildrop. For example this sets the default maildir (which is necessary otherwise the final maildrop script will not work):
{
MAILDIR="$HOME/mail"
}
If multiple filters must be all satisfied in an "and" relation, they can be prefixed by &&. For example, if the mail should be relayed if it is about foo bar, or only about foo from certain senders:
Subject: foo bar
Subject: foo
&& From: /foo@|bar@/
=> foobar
When the same header is checked in multiple, consecutive filters, only the first filter has to specify the header name:
From: foo@example.org
: foo@example.com
: bar@example.org
=> exfolder
The mails can be automatically marked as read with the mark seen command (requires maildrop >= 2.8.4, although you could use an older mailfilter from early 2017 with older maildrops ):
From: foobar
=> foolder
mark seen
This marking can also be done conditionally, e.g. to hide spam:
From: foobar
=> foolder
Subject: spam
mark seen
Multiple filters are separated by line breaks like paragraphs in markdown.
Subject: topic1
=> folder1
Subject: topic2
=> folder2
From: someguy
=> thatguy
mark seen
=> catchall
See tests/tests.pl for further examples.
This is highly experimental and mostly made to sort my own mails.
The folder used by => is always prefixed with $MAILDIR, which is currently not configurable, so you need to declare a variable MAILDIR.
From/To/Cc/Resent-To/Resent-Cc ignore the name part and only compare the addr.
The two commands => and mark seen should probably become more user configurable.
If you use contains filters like subject: .., the script should ensure that the resulting maildrop script is valid.
However, if custom regular expressions are used, e.g. subject: /.../, it does not check whether the regular expression is valid. So one should always run echo | maildrop to check if the mailfiltering still works after editing these expressions.
Dovecot uses mailfolders like $MAILDIR/.a.b.c for a folder c in b in a. Here we write such a folder as a.b.c