After dropping support for Microsoft's Sender ID antispam technology last month, AOL announced this week that it's once again supporting the technology, thanks to some changes Microsoft recently made. The changes make Sender ID compatible with the Sender Policy Framework (SPF) antispam technology that AOL and other companies are currently testing. AOL says it will begin testing Sender ID on inbound email to its online service by the end of 2004.
  
"We welcome and applaud Microsoft for its efforts," an AOL statement issued today said. "The new Sender ID specification is, without a doubt, proof that the standards process can work well." Earlier, AOL and other companies interested in antispam technologies complained that Microsoft's Sender ID patent application made the technology less attractive and less viable for open-source solutions. Microsoft changed its patent application to clarify that the company is seeking to patent only a certain method for determining whether an email message is valid mail or spam. That change was enough to mollify AOL, apparently.
  
Microsoft also noted that it will freely license the patented technology, and that companies that implement Sender ID are free to use their own email-scanning techniques. Whether this change will be enough to persuade open-source companies to support the technology is unclear, however.