Global-Domain-Hosting.com

Email client: Goldmine’s integrated email client (and no, we can’t switch)
Email provider: www.fatcow.com
ISP: Brighthouse Networks highest level of business-class cable modem service (without going to fiber)

The message is simply, "socket disconnected unexpectedly" as returned by the email client. Goldmine support blames the email provider (fatcow); email host blames the mail client (Goldmine).

I’ve changed the SMTP port to all of the available ports offered by the mail host, but no change.

Anyone?