Wednesday, October 20, 2010

Converting from mbox to maildir, procmail to deliver+dovecot+sieve

SkyHi @ Wednesday, October 20, 2010

I’ve been wanting to do this for a while, but too busy, too lazy and finally too worry that I might lose my mail archive…. etc…etc…etc..

Over last weekend, I bit the bullet and did it.  Partly because my DSL line was down, so there was no network activities, no mail, so might as well take advantage of the down time.  My next project is to drop AT&T DSL, I am tired of their bs.

Not meaning to get off the subject, but I am one of the earliest DSL sub in the neighborhood.  Got mine in ’96 (only 768k down/256K up).  I am about ~14-15000 ft from nearest CO, limit of DSL line.  Back then, Pacbell promised they will upgrade facility in the area so I can get faster speed.  Fast forward to 2009, 14 years later, still same old… and still crappy service.

Ok, back to converting from mbox+procmail+dovecot to maildir+deliver+dovecot+sieve.  My mail archive goes back a long way, still have emails from 1987 (UUCP/Usenet mail).  I’ve always used mbox format, as that was the default then, and since I never used qmail….

I do separate my mail into folders (just another mbox file) of course, otherwise my main mailbox would be in the gigabyte range.  I use procmail to filter incoming email into these separate boxes, to automate dealing with requests, to bounce spam, etc.  My .procmailrc is around 30K in size with lots of recipes, and also pulling in dozens of include files.

I knew that mbox is inefficient and that procmail is killing my system I/O, but sheer inertia kept me where I am.

After some research, I found — a Perl script — that will do most of the grunt work in converting an mbox file into maildir.   I am using Postfix for my MTA and dovecot for IMAP, so support for maildir is already there.  Supposedly, procmail supports maildir, but…

Here is the basic HOW-TO for converting mbox to maildir.

Basics: I am using Postfix, dovecot on FC11

1. Stop postfix and dovecot.

2. Install dovecot-sieve (and dovecot-managesieve if you have users beside yourself)

3. Edit /etc/postfix/ and change mailbox_command to /usr/libexec/dovecot/deliver

mailbox_command = /usr/libexec/dovecot/deliver -a “$RECIPIENT”

The -a “$RECIPIENT” part is if you want to use

4. Edit /etc/dovecot.conf

  • look for protocol lda { section and make sure this is there, add/uncomment/edit if not
  • # Support for dynamically loadable plugins. mail_plugins is a space separated

    # list of plugins to load.

    mail_plugins = sieve

    mail_plugin_dir = /usr/lib/dovecot/lda
  • look for plugin { section and look for these lines:
  • # Sieve plugin ( and ManageSieve service


    # Location of the active script. When ManageSieve is used this is actually

    # a symlink pointing to the active script in the sieve storage directory.



    # The path to the directory where the personal Sieve scripts are stored. For

    # ManageSieve this is where the uploaded scripts are stored.

  • Make sure /usr/libexec/dovecot/deliver exists and is executable.

5. If your mbox is in /var/spool/mail/yourname (or in /var/mail/yourname), i.e. mine is /var/spool/mail/tin, then you can run the following command to convert that mbox into maildir.

mb2md -s /var/spool/mail/tin

mb2md will automaticaly create a directory named Maildir in your home directory (i.e. it created /home/tin/Maildir for me).  The converted maildir files will go in there (from /var/spool/mail/tin).

My filtered incoming mail (via procmail) is in the mail directory of my home directory, i.e. /home/tin/mail.  There are multiple directories and multiple mbox files in there.

There are also directories such as .imap directory, created by dovecot.  Anything there that is not a valid mbox file will be ignored by mb2md.

So now run

mb2md -s /home/tin/mail -R

That should recursively travel into your mail folder and convert all mbox files there into maildir format in your Maildir directory.

I did found some mbox files that was ignored or failed to convert.  But manually running mb2md on those file worked, e.g. mb2md -s /home/tin/mail/missed-mbox-file.

To make sure there won’t be an accident, I renamed my mail folder to mail.old.  Then start up postfix, dovecot.

I’ll add more information about the .dovecot.sieve file later.