[Dovecot] mail extra field to override default mail_location for only certain users

[Sahil Tandon]

I am running version 1.1.1 with mail_location: maildir:~/Maildir.  This is 
working great as all our users have UNIX accounts with nologin shells.  New 
domains (and their users) are about to come online and we would like to 
migrate to a setup with virtual mailboxes/users.  From the wiki and comments 
within dovecot.conf, I see it is possible to do this piecemeal so both local 
and virtual users can co-exist during the transition.  My question is how to 
keep things working as they are for existing users/domains (which will be 
migrated later), and use the virtual mailboxes (and thus, a different 
mail_location) exclusively for the new users.  I understand that multiple 
userdbs and passdbs can be specified, and this will take care of 
authentication.  On http://wiki.dovecot.org/VirtualUsers#homedirs it is 
stated that "The userdb can return the mail extra field to override the 
default mail_location setting. Usually you shouldn't need this."  Where is 
this mail extra field defined?  In the userdb passwd-file or somewhere within 
dovecot.conf?  If the former, would something like this suffice (mind the 
wrapping):
                                                       
user at domain.org::5000:5000::/home/vhosts/domain.org/:/usr/sbin/nologin::mail=m
aildir:/home/vhosts/%d/%n                      

Thanks,
-- 
Sahil Tandon <sahil at tandon.net>