tried asking Adobe? I know nothing of lightroom, nor do I have a desire to learn. But if you are trying to set it up in the manner that is discussed in this article then Thunderbird does not factor into the equation.

If you were to select Thunderbird from the list, then the mail should be parsed into Thunderbird. But using the SMTP instructions only lightroom and your mail provider are involved (and your anti virus mail scanner if you have one).

By implication I think your provider is Yahoo, as you mention them. But a really good way to determine who your provider is is to use the name after the @ in your email address. Another is to use the name of the server. smtp.yahoo.com for example would make your provider yahoo.

I am guessing, but I think you will need to enable less secure apps in your settings on Yahoo, then get a provider that is in the business of sending email, not selling advertising. That way when you ask them questions they will not send you off somewhere else.

Thanks for the info. I do not have Thunderbird installed & got message from Yahoo something like someone was trying to access my account from unsecured site so your probably right about settings. This is much to complicated for me so I think I will forget about LR email & continue to drag & drop. Thanks again!

That is what Yahoo wants from you. Your eyes on their adds. So you are doing exactly as they want. Personally I don't look at their adds.