Have a MBP running latest El Capitan (10.11.6) and an iMac running the latest Sierra Public Beta. Both have the same 5 e-mail accounts configured: 1 iCloud, 1 Gmail, 1 IMAP, and 2 Exchange.
On my MBP I receive all my e-mail. On the iMac running Sierra, however, e-mail sent to my University Exchange account does not appear unless I quit and relaunch Mail. Interestingly enough, e-mail sent to my other Exchange account is working fine. It's not that my password is wrong or anything like that since the e-mail does appear when I relaunch Mail.
To be clear ... if I have Mail up and running on both systems then mail sent to my University Exchange account appears normally. But on the iMac it never appears unless I quit and relaunch Mail.
Anyone else seen this?
