The IMAP Calendar Proxy is a software that converts HTTP PUT requests of vcalendar data via an HTTP proxy.
Using this software presently may lead to a loss of calendar data, so it works more of a proof of concept. Furthermore, it's a bit slow when handling large calendars. Ideally, IMAP support should build into Mozilla, and this is simply a hack. However, feedback on its performance is highly appreciated. You can check the TODO file to see some features the developers aim to implement.
Sunbird has the ability to post calendars to a remote HTTP server via HTTP Put and synchronize via a GET before a PUT. This proxy runs on the same system that you run Sunbird on, and it then selects a specific folder and makes a connection to an IMAP server to retrieve all calendar data from that server and stores it in its memory.
Whenever there is a change to the calendar, it uses HTTP PUT to pass the differences to this proxy, which then determines what to do on the IMAP server (delete, add, or modify). Rather than posting the complete calendar back to the server, it only posts the differences.
It's important to note that running the proxy elsewhere doesn't offer any bandwidth savings because the HTTP PUT and GET are still processed over the network. Thus, it's better to run it on the same system.
The software requirements include Python 2.2.3 and 2.3.3 on Linux, although it's expected to work on newer versions of Python and other operating systems. The CommuniGate Pro IMAP server is the only tested server so far, but it should work with others as well.
In the most recent release, the software can now handle IMAP servers that don't send UIDNEXT info like Courier. Thanks to Ranieri Argentini for pointing this out.
Version 1.3: N/A