[imp] How configure and manage 2 mail domains in an horde installation

[Marco Maiani]

I have an horde3 installation with imp4, kronolith, turba,mnemo on 
Debian with Postgres.

In my agency we have two mail domains (example1.com and example2.com) 
and we'd like to manage them with only an horde installation because 
often some people, that have mail accounts on different domains, works 
in the same group and need to share calendars.

Is it possible to have, on login page, an option where the people can 
choose the domains where they have their e-mail? (the domains and the 
mails are on the same server)

Thanks

Marco