Yep. There is something wrong with the Mail app. Here's my backstory:
Before posting my suggested solution, I spent around two hours Wednesday (Sept 18) on a tech support call with senior Apple advisor regarding this issue. Eventually they had me install MS Outlook. We successfully connected to my mail server using Outlook.
The Apple senior advisor said that if I could get the screen shots and application logs uploaded to them, he might be able to get back to me by Tuesday (Sept 24), because he was out of the office on Monday (Sept 23). The advisor was personable and pleasant. I have nothing against him personally. Nevertheless, he was not empowered adequately to resolve my issue or escalate it in a timely manner. So, I'm throwing Apple as a company under the bus for creating a problem with the Mail app they could not resolve for me or others.
I could not wait to resolve the issue. I am no fan of MS Outlook. So, I looked to other third-party mail apps.
Moving off of Apple Mail to a third-party mail app is a viable solution when:
- Your business email accounts are dead in the water because of the issue
- Apple support is unacceptably slow to respond to the issue
- Apple's time to market with an updated release that fixes the issue is unknown
- Perceptions of many long-time users are that the overall stability is in question
- Other available solutions work