Apple Mail on macOS 10.14.4 Loses Connectivity to the Gmail SMTP Server
Recently I have noticed that the Mail app version 12.4 (3445.104.8) running on macOS Mojave version 10.14.4 (18E226) will lose connectivity to the Google Gmail SMTP server over a period of time. I am unsure as to the exact period of time that causes the connectivity loss, but would estimate that it is around 2 hours. Apple Mail reports Gmail as offline, and won't take it back online. Quitting out of Apple Mail entirely, and restarting the application will restore connectivity to Gmail. However, this is a temporary fix as the issue recurs again after another period of time. I believe that this behavior began with the update to macOS 10.14.4. Gmail previously worked without issue with Apple Mail from many years.
The issue has also been recently reported on the Google Support forums as Why does Apple Mail keep loosing connection to the Gmail SMTP server? As far as I know, there has been no satisfactory answer from either Google or Apple or the community. Many believe that it may likely be more of an Apple issue than a Google issue, as the issue appears to have started with the release of macOS 10.14.4.
iMac Pro, macOS 10.14