Yes, the app password  is exactly what worked for me....but unfortunately, yahoo has their own set of rules. So it now takes me about an hour to email 130 invoices because yahoo limits the number that will send with the app password code, so I have to keep going back to get new ones after every 13 to 19 emails sent. Then I also have to wait a limited number of minutes, approx 5, or it fails and if I keep trying then it thinks my email has been hacked and I have to reset my yahoo email password. Looking for a better option than yahoo right now....but it's my busy season so no time for research right now.