[horde] login name/default settings question

[Gary W. Smith]

I have a little problem we are trying to resolve.  The login names do
not match the email addresses for our users.  We have prefixes for all
users names based on type and the users are also segregated by domain
name.  Here is an example

dom1_user1 has email address user1 at dom1.com
dom1_user2 has email address user2 at dom1.com
dom2_user1 has email address user1 at dom2.com

You get the picture.

So if a user logs in for the first time their default email address
doesn't match their true address.  If user dom1_user1 logs into the
system (by going to www.dom1.com/horde/imp) a default profile is created
with dom1_user1 at dom1.com.  This doesn't work as there is no email
address dom1_user1 at dom1.com.  

We have tweaked the servers to default the domain name based on the URL.
This part was easy.  What we would like to do now is tweak the piece of
code that creates the default profile.  I have poked around but haven't
been able to successfully do this.  My goal would be to tweak that
section of code to strip off prefix_ (as these are the standards for
these account) if it exists.

Does anyone know of a simple way of doing this?  Or can someone point me
to the section of code where this is set?  

Gary Wayne Smith