Repeated Authorization Error Issues with My Yahoo Mail Account

Although my Yahoo Mail account appears to be able to send and receive mail just fine - I continuously receive pop-up requests from eM Client for a correct password to be entered. The eM Client pop-up dialogues each indicate escalated authorization issues.

This is especially troubling in that I am enjoying the product and was seriously considering purchasing the license at the end of the trial.

PLEASE ADVISE!

I am happy to be contacted directly via phone/email/chat etc. to remedy this problem.