Title: Convert mailbox to maildir with dovecot
       Author: Solène
       Date: 17 January 2017
       Tags: unix email
       Description: 
       
       I have been using mbox format for a few years on my personal mail
       server. For those who don't know what mbox is, it consists of only one
       file per folder you have on your mail client, each file containing all
       the mails of the corresponding folder. It's extremely ineficient when
       you backup the mail directory because it must copy everything each
       time. Also, it reduces the system cache possibility of the server
       because if you have folders with lots of mails with attachments, it
       may not be cached.
       
       Instead, I switched to maildir, which is a format where every mail is
       a regular file on the file system. This takes a lot of inodes but at
       least, it's easier to backup or to deal with it for analysis.
       
       Here how to switch from mbox to maildir with a dovecot tool.
       
           # dsync -u solene mirror mbox:~/mail/:INBOX=~/mail/inbox
       
       That's all ! In this case, my mbox folder was **~/mail/** and my INBOX
       file was **~/mail/inbox**. It tooks me some time to find where my
       INBOX really was, at first I tried a few thing that didn't work and
       tried a perl convert tool named **mb2md.pl** which has been able to
       extract some stuff but a lot of mails were broken. So I have been
       going back getting dsync working.
       
       If you want to migrate, the whole process looks like:
       
           # service smtpd stop
       
           mail_location = mbox:~/mail:INBOX=/var/mail/%u   # BEFORE
           mail_location = maildir:~/maildir                # AFTER
       
           # dsync -u solene mirror mbox:~/mail/:INBOX=~/mail/inbox
           # service smtpd start