A host of software companies, security firms and Internet service providers met in Chicago to urge corporations and bulk message senders to adopt e-mail authentication technologies. The technologies, known as Sender ID and DomainKeys, aim to allow e-mail recipients to positively identify the sender of an e-mail message and hold the promise of giving service providers the tools they need to effectively end spam and phishing attacks. Yahoo!, the creator of DomainKeys, receives about a billion messages a day signed with the technology though Yahoo! Meanwhile, more than 2.4 million domains are publishing the additional domain information required for Sender ID, up from 20,000 two years ago, according to Microsoft, which has spearheaded the Sender ID initiative. In total, more than 35 percent of e-mail is authenticated in some way and 21 percent of Fortune 500 companies publish Sender ID records, according to Microsoft.