There was a thread several weeks (or months) ago on webmail applications.
I didn't like any of the options and only found few that I did but they were either expensive or not maintained.
So ... I raised the question on the Catalyst Framework list about Perl based webmail apps and got nothing usable. It came down to what would it take to build a Perl (Cat) webmail app.
Several others on the list got interested so we decided to build it. The main issue I run into is my lack of understanding of the ins-and-outs of the IMAP specification and the features that come with using Dovecot. (Oh yeah. Dovecot was the preferred IMAP server!)
Another project I'm working on uses IMAP and what I found was there is a great quantity of Perl modules for dealing with IMAP. A great quantity! Unfortunately many of them assume a deeper knowledge of IMAP than I have so are very confusing.
What I'm looking for is a good reference, besides the RFC, on IMAP. Anything out there? Electronic or dead-tree is fine. (A book of Dovecot would be neat too.)