How can I get Spectrum Charter email working with Mail in macOS 10.15?

Mail stopped working with Charter accounts in macOS 10.15. I can connect just fine using Big Sur.

I deleted all Charter mail accounts, removed all the keys in Keychain and removed all the cache files. I can connect to all mail accounts, but, Charter's. I see posts about this all over Apple's forums and others.

Again, same exact settings work in Big Sur but don't in Catalina. (and why can't Apple's spell check actually spell it's own operating systems correctly?)

If I use imap.charter.net and smpt.charter.net for IMAP I can finally connect but am warned the password is sent insecurely, so that's useless. No other incoming / outgoing combinations work.