Convert Maildir to mbox

Question

Im changing hosts and i need to convert my maildir accounts on my old server to mbox on my new server.

Any ideas on the best way to do this?

I found this:

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Answer 1

If one needs to convert a maildir account into a mailbox account without setting mailservers, one can use the mailbox library of python. If one has a single maildir folder to convert, one can use this small (10 lines+comments) python script found here. If one has subfolder, one needs to explore the subfolder structure, which is different between the two formats. This gives the following script :

#!/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
    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')

Answer 2

If you have access to both servers via imap (or can temporarily arrange it), you might want to consider using an imapsync tool, eg:

http://freshmeat.net/projects/imapsync/

If that won't work, you should be able to ignore the dovecot files, but beware that you'll likely lose information like which messages are read and any flags set on the messages. (The imapsync method would preserve all those things.)