dovecot - Sep 2013 - Change mail_location for one user?

Hello, I'm running the latest version of dovecot on Linux with mbox 
mailboxes.  Everything works fine.  So in my dovecot config I have 
mail_location = mbox:~/mail:INBOX=/var/mail/%u

I would like to now change the mail_location for one user in an attempt 
to slowly migrate to Maildir format.  I'm confused how to do this.  I'm 
running shadow passwords:

$: doveconf -n passdb
passdb {
   driver = shadow
}

Testing any given user gives:
$: dovecot user sarah
field   value
uid     1478
gid     116
home    /home/sarah
mail    mbox:~/mail:INBOX=/var/mail/sarah
system_groups_user      sarah

What would I have to do to make only sarah's mail_location ~/Maildir 
now?  My userdb is:
$: doveconf -n userdb
userdb {
   driver = passwd
}

I tried following the wiki's but its confusing.  Thanks for any help or 
tips.

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On Thu, 12 Sep 2013, Scott Galambos wrote:
> Testing any given user gives:
> $: dovecot user sarah
> field   value
> uid     1478
> gid     116
> home    /home/sarah
> mail    mbox:~/mail:INBOX=/var/mail/sarah
> system_groups_user      sarah
>
> What would I have to do to make only sarah's mail_location ~/Maildir
now?  My
> userdb is:
> $: doveconf -n userdb
> userdb {
>  driver = passwd
> }
>
> I tried following the wiki's but its confusing.  Thanks for any help or
tips.
you need to pass "Extra Fields" to Dovecot, see last example in:
http://wiki2.dovecot.org/UserDatabase/ExtraFields

"passwd-file" is similiar to "passwd", but I don't know,
if you break
something (outside Dovecot), if you add the last field to /etc/passwd.

Because Dovecot supports multiple userdb's, you could add a passwd-file 
userdb _before_ passwd userdb, copy the line of sarah from /etc/passwd 
into that new file and add the extra fields there. See 
http://wiki2.dovecot.org/AuthDatabase/PasswdFile

userdb {
 	driver = passwd-file
 	args = username_format=%n /etc/dovecot/imap.passwd
}
userdb {
 	driver = passwd
}

- -- 
Steffen Kaiser
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