[horde] Authorisation and virtual mail users

[Jānis]

Hi!

I am trying to figure out how to achieve the following setup:

there is the linux system with real users but for some considerations  
unknown to me it is of utmost importance to use virtual accounts for  
e-mails (postfix/dovecot/postfix-admin/mysql).
Currently evrth works, but the logging in twice is necessary - first -  
for the Horde framework, except Imp, using sys user credentials and  
the second - using virtual email address if one is going to read/send  
e-mails.

Sys users can not be virtualized because they have huge personal homes there

Is it possible to achieve single authorization for such strange system?

Janis