I've honestly not noticed much difference in spam filtering with free email accounts these days. At least those from the 'big providers' like Google, MS, Yahoo, etc. Heck, even SpamAssasin (formerly SpamYourAss) is decent the past few years.

Well, 90% of one's max HR is simply that; to a certain point, it'll be higher the more fit you are. So unless you have a heart condition, intervals aren't going to kill you (especially the one minute intervals referenced in the NYT link).