I now understand what you are saying. While Imp was in beta a new pref 
was introduced 'mail_domain', this according to docs/changes overrides 
any values set within config/servers.php.  Problem was solved by 
emptying pref 'mail_domain'.

I've used the maildomain as this used to work with releng versions, 
but how do I now make it dynamic. Is there an example somewhere or 
documentation how to do it.

You need to set the correct from address with a preference hook. You 
probably rely on the maildomain setting. Well, you can use that to, 
but need to make it dynamic.

If I have installation that has two mail servers to different domains 
eg. example.com and cs.example.com. When I log in I have to choose 
correct server and I get correct greeting message eg. "hello 
user@example.com" or "hello user@cs.example.com". But the problems 
lies with default profile being wrong. No matter what server I choose, 
then default profile is always  user@example.com. This obviously 
causes problems bacause user@example.com might not be the same as 
user@cs.example.com and because this default profile identity is used 
as sender address if from_addr preference is disabled.



The Horde releng version did this correctly and user got correct 
default profile and from_addr based on usename and server/domain.