I hope that when you were talking to Spectrum they told you the exact email server settings you will need. To manually configure an account, you will need to have the following details which can be supplied by Spectrum.

- Incoming mail server and port (for example, "pop.example.com" and port 110 or "imap.example.com" and port 143)

- Outgoing mail server and port (for example, "smtp.example.com" and port 25)

- Security settings for the connection with the server (for example, "STARTTLS" or "SSL/TLS" and whether or not to use secure authentication)

First, turn OFF Thunderbird's Account Hub feature (Settings | General | Account Hub>, uncheck "Create accounts in the new Account Hub." It's labeled "Experimental", and while it picks the correct settings most of the time, sometimes it doesn't.

- Go to (on Windows) <Tools | Account Settings | "+ New Account" button | Mail Account...>

- Fill in your, email address, and password. You can click the "Configure manually" link and enter them there, or you can press Continue, and Thunderbird will consult its database and suggest settings for you. If they are incorrect, you will be prompted to enter the correct settings.

Here's Thunderbird's help page on the subject. It's a little out of date and doesn't reflect the current interface, but the basic info is correct.

https://support.mozilla.org/en-US/kb/manual-account-configuration

I appreciate your help. I disabled the Account Hub feature, but that didn't change the result. All the other steps are things I've done before (several times) including a very patient walk-through by Spectrum support by phone. I always end up with the same error message I described. I just went through the entire process again as per your instructions (entering appropriate information) and still get the same error message: "Thunderbird failed to find the settings for your email account." Which really does seem odd since Tbird says it pulled those setting from the provider's server.