User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_1) AppleWebKit/602.2.14 (KHTML, like Gecko) Version/10.0.1 Safari/602.2.14 Steps to reproduce: Go to http://bad.neon2.ml/?i=2 and firefox trys to open the mail app on macOS nonstop or it might freeze. I would a video on youtube talking about going to this site, I did not create the website or the exploits but I did report it. And I attached a the source code from the website above to this bug report. I tested this on torbrowser and it causes tor browser to freeze. Actual results: firefox trys to open the mail app on macOS nonstop or it might freeze Expected results: Firefox should not open mail nonstop and it should not freeze.