The purple box ad just recently appeared on my Yahoo email account page. Is there a way to block or cancel it, using Firefox?

Try this trick, Yahoo purple box block.

This is a box ad that spans the whole field at the top of Yahoo email messages.

Like this

Sounds like Yahoo is spamming you, no solution for that. Can you filter email as spam, for that address?

Here is a prior discussion.

Apparently $50 will solve the problem.

If you’re referring to the purple-highlighted spam that appears in your inbox, Firefox Adblock Plus blocks that for me, and it’s free.

Thanks, @Brian1946. I’ll try that.

It worked!
Thanks, @Brian1946!

If you say OK, it will install Yahoo junk and force you to use Yahoo Search. Can’t use Google for search after that! Your home page is also changed to Yahoo.