Spectrum email not working on MacOS

I have been using the same email address for almost 20 years through earthlink, charter, and now Spectrum. Within the last year, the email account has stopped working with the default Apple Mail client on my iMac (MacOS X 10.14.2). I have had multiple conversations with Charter and Apple tech support and they blame one another. There is an archived thread on this forum describing much the same thing. I spoke with the Spectrum 1st level tech and eventually was elevated to a 2nd level who provided the following information:

If you are able to sign into our spectrum.net site and use the email to send and receive there then the email is working for your account. When we use a 3rd party email client like Apple Mail, we are putting in server identifying information and security details to have that software interact with the server to provide a different layout. The settings we provide are used for all third party email client types. Recently, we have had a lot of customers reporting issues syncing their email with Apple Mail on various Apple products. We teamed up with Apple for a solution and the result was that a solution would need to be applied on THEIR end with an upcoming update to the mail client. The issue is that Apple Mail autocompletes several of the settings based on the server name and is currently auto-completing with inaccurate server settings.

While i do understand the convenience of using the email through your preferred email client, we cannot provide further assistance than ensuring you have the proper settings for the email which are found in the link you originally posted in this chat.'

Obviously this is infuriating. The user is expected to simply wait until these two companies solve their differences on an issue relating to email, one of the most tried and true communication systems since electronic communication was invented. Ridiculous.

I would recommend all Spectrum users abandon their email products in favor of others that are maintained properly. The Spectrum webmail is incredibly buggy and slow. The Spectrum spam filters are terrible, and so most of the webmail experience involves manually deleting spam. Spectrum provides a terrible customer service experience along with deficient technical capabilities.

Additionally, the first level technician provided none of the useful information posted above, instead telling me that the only thing that Spectrum could do was provide the settings, everything else is up to the user/Apple to solve. I would think that letting users know that there is a known issue in compatibility between the Mac and Spectrum would be the first thing a competent ISP would do.