For me the keymap switcher icon worked initially in Beta (64bit) but broke after an update I did through Software Updater. I think it’s broken for the last 2 haiku system updates.
If that fixed it, there has been a regression. I didn’t switch from beta back to the nightlies until mid December. I have yet to see the mail icon in tray in 64bit.
IMAP is completely broken in beta1, pop3 had some bugs too. Everything is now fixed in nightlies so I’d suggest to use that. Current nightlies have tons of other bugs fixed too.
Beta1 was a code freeze back in September. This means any new features and fixes will most likely not be back ported to it, except for security patches. For more recent developments, you either need to use the nightlies or wait until the next official release later this year. I highly suggest checking out the nightlies.
This is most likely going to be the same proceedure in the future, as this is the same as was done with the Alpha releases.