Trouble getting Mozilla Thunderbird accepted for DirectLink mail accounts

When adding email accounts to Mozilla Thunderbird, when I test our the settings, I get an error message "unable to connect your account to mail.canby.com. As a result since August 6 I have been unable to access my email accounts with error code as the server is not responding or cannot get emails. Have not been able to get assistance from our internet service provider DirectLink in Canby, OR. Have been in Live Chat with about 6 techs who basically have given up and said contact Thunderbird to solve the problem. Anyone have any advice? I can read emails on mail.canby.com. Thanks. redacted@canby.com