dovecot - Aug 2006 - [long message] problem with imap authentication process

Hi guys,
this is my first message in list.
i've installed dovecot 1 RC 7 from sources and set it
up with postfix as a pop3 mail server: all worked
perfectly.

Now i would like to set up a local web mail interface;
most web mails (eg horde,squirrelMail) use imap to get
mail; so i've to set up dovecot imap server.

I've set up imap settings in config file and added
imap
to protocols (i don't use ssl encription):
> protocols = pop3 imap

But when i run dovecot, i get "USER environment
missing", what does it mean? :
> root at mailer:~# for i in /var/log/mail.*;  do echo >
$i ; done
> root at mailer:~# echo $USER
> root
> root at mailer:~#
> root at mailer:~# /usr/sbin/dovecot
> root at mailer:~# cat /var/log/mail.info
> Aug 30 15:58:42 mailer dovecot: Dovecot v1.0.rc7
starting up
> Aug 30 15:58:43 mailer dovecot: imap-login: USER
environment missing
> Aug 30 15:58:43 mailer dovecot: Login process died
too early - shutting down
> Aug 30 15:58:43 mailer dovecot: child 3929 (login)
returned error 89

As you seen, $USER environment variable was set;
authentication process user id (in config file) was
set to root. Mail users are virtual users and their
account informations are stored to a passwd-like file.

I searched in the source code the error string and
found this

dovecot-1.0.rc7/src/imap/main.c: 
>        user = getenv("USER");
>        if (user == NULL) {
>                if (IS_STANDALONE())
>                        user = getlogin();
>                if (user == NULL)
>                        i_fatal("USER environment
missing");
>        }
This is the only occurrence of the error. This code is
simple, Why getenv("USER") returns NULL ? variable was
set when i run dovecot....

mmm..Any suggestion? Is this a bug of a process
cloning /forking system in dovecot?
I looked in mailinglist archives for a solution but
nothing found.


Anyway can you suggest me any web mail with simple
configuration with postfix+dovecot virtual accounts?
What about oMail-webmail? is there a way to integrate
it in dovecot authentication ?

Any help appreciated!

Valerio