You get 2 days???...impressive.
I'm always on from 7am-7pm and if I talk for anymore than 30 minutes during that day I've got charge the phone at 4pm so it will be usable for the night. It is 4 months old and I don't use anything else during the period (no blue tooth, no wifi).
As for the sound alert I get this too. At night when synch is every 30 minutes if I take the e-mail in outlook the phone will pick iot up at synch time and flash the light as a new e-mail, but play no sound.
It sometimes does the same during the always on period. It is not constant so I haven't looked into it much, but I've noticed once it recieves one without sound it won't play a sound again for new e-mails until I unlock the keys and enter MfE..another annoyance.