The t.co short URL service from Twitter is used more than any other by spammers to deliver links to pharmacy websites that distribute counterfeit products, according to spam fighting firm.Andrew Conway from San Francisco-based Cloudmark, a company that offers protection against email threats, reports that at the moment, more than half (54%) of the short links blacklisted by them use Twitters service.He said that the spam using t.co short links comes in outbreaks that last between four a…