Groupware solution with qmail

Hi friends,

I'm searching the mode of make a groupware service with my current qmail-ldap installation.

I need a service wich offer mail (pop/imap/web) and allow share address book, calendar and task (web/outlook/evolution/thunderbird...).

I have been reading and at this moment, I think that Kolab+Horde+qmail-ldap can cover this requeriments. Kolab works with postfix by default, but I think that it's possible disable mail function and do it with Horde+qmail-ldap.

So, the service will be:

- Mail -> qmail-ldap + Horde (webmail)
- Calendar, task and add.book -> Kolab + Horde(web)

What do you think? Maybe is it time of migrate to postfix due to each time lower support of qmail?

Thank you very much,
Spamis