[imp] Migration from Squirrelmail?

[Josh Trutwin]

I have been looking through the documents out there and haven't been able to find anything to help with a large migration to Horde/IMP from a SquirrelMail environment.  Anyone have any pointers/gotchas?

For virtual hosting, do I have to setup an instance of Horde/IMP on every single virtual host?  What I had done with SquirrelMail in the past was use Apache redirect to have all URLs like:

http://www.virtualhost.com/webmail/ or http://mail.virtualhost.com/

all redirect to:

http://www.webmailhost.com/webmail/

This way I only have to maintain one webmail installation for possibly 100's of domains.  But I notice in Imp's server.php config file:

" * realm: What to append to usernames for preferences and Horde
  * authentication to prevent login clashes on virtual host setups."

" * maildomain: What to put after the @ when sending mail. i.e. if you
  * want all mail to look like "From: max at the-triumvirate.net" set
  * maildomain to "the-triumvirate.net". It is generally useful when
  * the imap host is different from the mail receiving host. This will
  * also be used to complete unqualified addresses in the compose
  * screen."

These seem to imply that I need a seperate servers.php config file for every virtual host.  

I am not entirely sure if this is a concern for me.  I use qmail/vmailmgr for virtual hosting and everyone's username is essentially unique because their username is their full email address.

I really want to move to Horde/Imp as I have heard so many good things about it, but these two are kind of show stoppers at the moment.  My apologies if I missed some obvious documentation.

Thanks,

Josh