Procmail, the misunderstood tool

When I first came in contact with procmail, I refused to use it. It is not really intuitive and without a deeper knowlege of regular expressions you are not able to understand anything. Times have changed - let's rock!

A long time ago I removed my kmail rules and created server-side-rules with procmail for a simple reason: Webmail! Squirrelmail rocks when you're not at home, but a 2GB INBOX is not the way I wanted to do it. So Folder were needed. Over the years, lists came, lists went, and even with this cool KDE fish KIO slave (Link ssh ressources on you desktop) a one-click-open, one-click-save with your favourite editor was too much work for me *g*.

Perl - extract the List from the mailheaders

Lists have (should have?) a header like this:

The follwing code creates form mailinglistname@domain.tld a folder name domain,tld / mailiglistname. Don't be surprised, a point is the folder-seperator for IMAP Folder, so I had to replace '.' with ','. The foldername is printed out on STDOUT and can be read by procmail.

Withing procmail I run the script:

#Pipe the mai through the listextractor
#return value LIST: "domainpart.localpart"
:0c
* ^list-post
LIST=|perl /usr/local/bin/listextract.pl

#Save the mail inside the maillists directory
:0
$DEFAULT/.maillists.$LIST/

Here is the perl script:

#!/bin/perl

# extracts the listid from a mail via stdin and returns a valid foldername

# read by line...
while () {

  # has a list-post header?
  if ($_ =~ m/^list-post: /i) {

    if($1 ne "" && $2 ne "") {
      $localpart = $1;
      $domainpart = $2;

      # . replace with ,
      $domainpart =~ s/\./,/g;

      # . replace with _
      $localpart =~ s/\./_/g;

      print $domainpart . "." . $localpart;
      exit 0;
      }
    else {
      die "unexpected error: list-post found, but not parsable. ";
      }
    }
  }
die "no list-post header found - this is NOT a list mail\n";

It's amazing how easy it was to create this little scripts (full files are attached). Please feel free to contribute comments!