Yesterday, Microsoft announced that it will submit a proposal to the Internet Engineering Task Force (IETF) to make its Caller ID for E-Mail technology an industry standard. Caller ID for E-Mail is an IP-based authentication scheme for ensuring that an email sender's return address is legitimate. Microsoft hopes that broad adoption of this technology will end one of today's biggest problems with spam: Hostile messages often seem to come from friendly sources because making email messages appear to come from someone else is easy.
  
Microsoft's submission is "imminent," according to company representatives, and will occur this week or next. But Microsoft isn't the first company to suggest a solution to the spam problem. Last week, Yahoo! submitted to the IETF its DomainKeys solution, which seeks to achieve the same results as Caller ID for E-Mail by using a digital-signatures-based method. And AOL is testing yet another scheme, dubbed Sender Permitted From (SPF), which uses a DNS-based database to check the authenticity of incoming email messages.
  
AOL and Microsoft say that they're working together to find common ground, and neither company describes the various proposals as competitive. "AOL will evaluate and test Caller ID \[for E-Mail\]--along with other proposals--in our ongoing effort to establish some much-needed email identity on the Internet," AOL said in a statement issued this week. Microsoft, meanwhile, corroborated that Caller ID for E-Mail, DomainKeys, and SPF could work together as a concentrated solution for authenticating email messages.