I'm experiencing problems on macOS Mojave 10.14.2 with an Exchange Mailbox in Apple Mail. The Exchange Mailbox account only updates once I click
Mailbox > Rebuild.
According to the Connection Doctor (
Window > Connection Doctor), all connections work properly. Outgoing mail also works. With the same setup on my iPhone 6, iOS 12.1.13, there are no issues and the inbox updates promptly. The issue seems to be related to the Apple Mail on my Desktop computer, and to Exchange accounts only. My Gmail (IMAP) account in Apple Mail works as expected.
How can I troubleshoot the issue, when one of several mailboxes won’t show new mails?