I recently updated to the Sierra Dev build. Ever since this change, I'm unable to stay reliably connected to my exchange server for work. I've deleted the account and gone through the set-up process again. This took several attempts before the username and password verification worked. Then I was up and running for about 30 mintues before I was interrupted by a password prompt again while drafting a new message and no matter how many attempts I make I cant get the password validated again. Any thoughts?