I'd like to take this chance to bring everyone up to date on the status of JBMS. It may look like we're in a lull but that could not be further from the truth.
The main development that is happening:
IMAP: Coming along. I have a pretty unstable branch on my local. As soon as it is ready I'll commit it, but don't expect to see progress on a daily basis. This is going to be one of those spurt-lull-spurt type commit cycles. Doesn't mean we're not working just that I won't commit something that isn't working, breaks the build or breaks all of our unit tests. Expect to see a big commit in a week or two.
SpecMail/Benchmarking - This has been a tremendously helpful effort. I can't claim much credit for it. Phillip Thurmond from JBoss's QA lab has done all of the real work. I just pressed a couple buttons on JBMS. While Specmail has been useful and we will continue to use it, it did point out the need for a simpler benchmark with less restrictions. I've got some preliminary code for this that I'll be committing soon. I can't tell you how well JBMS did in the benchmarking because our network isn't yet set up to comply with the run rules and some of the restrictions. What I can tell you from this and from my trip to a production JBMS site is:
Use PostgreSQL and tune it
Heap and GC matter, so tune those
CPU doesn't matter
RAID 1 matters (and we don't have that)
Tune your minimum DB pool size (next version has more sensible defaults)
This is KICKING and we're using Adobe's Flex/Flash technologies. You can find this in HEAD. You'll need the latest flex framework to compile this. The core GUI is basically finished so far as webmail. It presently only talks to the filesystem but that work is under way.
Calendaring works already. There is a decent Struts/Tiles/Freemarker based GUI that you can use today. Work is beginning on the Flash/FLex based version.
Bug Fixes/minor tweaks:
Despite all of the new features in the M5 release, I think it will also increase stability, scale and performance! Though M4 has been pretty decent so far.