I don't use yahoo/hotmail/google mail. I spent over an hour speaking with the QuickBooks Support Team and all that happened was that I was transferred over to the sales department and some guy wasted my time by very aggressively attempting to upsell me on my QuickBooks program, giving me a quote that equalled to about $1000 per year for an upgrade. Ridiculous. Since tech support thought I needed to upgrade my software, my client spent $78 for a non-subscription based, non-profit desktop version that we found ourselves online. That was fine, but it didn't solve the problem. I went through all the steps listed here and in other searches with no luck. I called my email provider and they suggested I unclick the SSL Certificate box. That worked.