Convert dovecot maildir to mbox format (local or on mailserver)

md2mb.py

#!/usr/bin/env python 
# -*- coding: utf-8 -*-
"""
Frédéric Grosshans, 19 January 2012
Nathan R. Yergler, 6 June 2010

This file does not contain sufficient creative expression to invoke
assertion of copyright. No warranty is expressed or implied; use at
your own risk.

---

Uses Python's included mailbox library to convert mail archives from
maildir [http://en.wikipedia.org/wiki/Maildir] to 
mbox [http://en.wikipedia.org/wiki/Mbox] format, icluding subfolder.

See http://docs.python.org/library/mailbox.html#mailbox.Mailbox for 
full documentation on this library.

---

To run, save as md2mb.py and run:

$ python md2mb.py [maildir_path] [mbox_filename]

[maildir_path] should be the the path to the actual maildir (containing new, 
cur, tmp, and the subfolders, which are hidden directories with names like 
.subfolde.subsubfolder.subsubsbfolder);

[mbox_filename] will be newly created, as well as a [mbox_filename].sbd the 
directory.
"""

import mailbox
import sys
import email
import os

def maildir2mailbox(maildirname, mboxfilename):
    """
    slightly adapted from maildir2mbox.py, 
    Nathan R. Yergler, 6 June 2010
    http://yergler.net/blog/2010/06/06/batteries-included-or-maildir-to-mbox-again/


    """
    # open the existing maildir and the target mbox file
    maildir = mailbox.Maildir(maildirname, email.message_from_file)
    mbox = mailbox.mbox(mboxfilename)

    # lock the mbox
    # comment out mbox.lock() if u run this script on a local machine
    mbox.lock()

    # iterate over messages in the maildir and add to the mbox
    for msg in maildir:
        mbox.add(msg)

    # close and unlock
    mbox.close()
    maildir.close()

#Creates the main mailbox
dirname=sys.argv[-2]
mboxname=sys.argv[-1]
print(dirname +' -> ' +mboxname)
mboxdirname=mboxname+'.sbd'
maildir2mailbox(dirname,mboxname)
if not os.path.exists(mboxdirname): os.makedirs(mboxdirname)

listofdirs=[dn for dn in os.walk(dirname).next()[1] if dn not in ['new', 'cur', 'tmp']]
for curfold in listofdirs:
    curlist=[mboxname]+curfold.split('.')
    curpath=os.path.join(*[dn+'.sbd' for dn in curlist if dn])
    if not os.path.exists(curpath): os.makedirs(curpath)
    print('| ' +curfold +' -> '+curpath[:-4])
    maildir2mailbox(os.path.join(dirname,curfold),curpath[:-4])

print('Done')