webmail solution

[Dave]

Hello,
    I'm looking for experiences with a webmail solution. I want to use 
postfix as my mta and on a freebsd6 machine. The users who will be using the 
server probably would do better with a webmail package so they can get to it 
from anywhere. The box already has apache and php so i don't think that'll 
be an issue. One thing i'm uncertain is whether to offer direct pop/imap or 
their equivalent encrypted counterparts or just do it all through webmail.
    Experiences and recommendations welcome.
Thanks.
Dave.