Phishing emails often pose as being sent by major league sites rather than princes from far-flung countries, but Twitter's implemented a new measure to stamp out phonies that borrow its name. Costolo and Co. announced that, earlier this month, they began leveraging a tech called DMARC that establishes a way for email providers to authenticate senders and reject messages penned by impostors. While the DMARC specification does need support from e-mail services, outfits including AOL (wh
