What WildScribe said.
I get more than 200 e-mails a day, which means things can get buried very quickly and I don't even bother to open e-mails when the subject lines indicate that they've come from a public relations firm or from a sender who is not offering me very specific information.
When you get that volume of e-mail, you become adept at quickly scanning subject lines and deleting the stuff that doesn't give any indication of its contents.
On a related note, if you don't get a response, send it again. These days, media companies are short-staffed and editors are overworked. It's entirely possible that the editor did not see your e-mail or simply skipped over it on a busy day, and that's never personal.
Good luck.