When opening Yahoo, via the envelope icon at the upper right area of the page near the address bar, my inbox page is briefly flashed, but then immediately goes to a "compose" page without request. The "from" address bar is filled in with my email address, and the first line of the body of the email contains the address of the last website visited. Example: while visiting this page to post my question, I clicked on the envelope icon, and I was directed to a "compose" page with the Mozilla site filled in attached is a Snipped screen shot of that page.

This behavior doesn't happen when tested with Chrome. I can't say exactly when it started, but it's been at least for a few months. Searched the Yahoo forum but wasn't able to find any solutions there. Hope you can help - thanks.