As far as qmail, do yourself a favor and just use the rpms at Bruce Guenters site
http://em.ca/~bruceg. Of course if you aren't running an RPM distro you will have to do it yourself. Bruce's stuff has all the patches you are likely to need, and some great scripts for setting up services ( I actually run all my aolservers with these also).
As for webmail, just remember, security flaws, security flaws, security flaws. Thats right, javascript is evil. Also, you may wish to nix qmail in favor of just using Courier (which uses Maildirs).
