Microsoft Corp is stepping up the pressure on email senders to adopt its Sender ID spam-fighting technology despite problems that could send up to 10% of legitimate messages to junk folders.
By the end of the year, Microsoft's Hotmail and MSN services will get more aggressive at rejecting mail sent through companies or service providers that do not register their domain names with the Sender ID system.
Sender ID seeks to cut down on junk email by making it difficult for spammers to forge email headers and addresses, a common technique for hiding their origins.
The system calls for internet service providers, companies and other domain name holders to submit lists of their mail servers' unique numeric addresses. On the receiving end, software polls a database to verify that a message was actually processed by one of those servers.
Although only a quarter of email messages now carry the proper Sender ID information, Microsoft believes it needs to begin requiring Sender ID to do a better job of cutting down on junk email, said Craig Spiezle, director of Microsoft's technology care and safety team.
"We have a solution that works for about 90% of mail today," Spiezle said. He said Microsoft will continue to fine-tune its spam filters to account for the remaining cases.
Although the standard-setting Internet Engineering Task Force dissolved a working group on Sender ID in September, partly because of a dispute over Microsoft's claims to a patent, Microsoft and other companies were encouraged to continue pushing their technologies in the marketplace.
For the past six months, Microsoft's Hotmail and MSN services have been checking Sender ID records as one test in determining whether a message is junk.
Microsoft began posting a warning for users on top of messages whose numeric addresses don't match those in Sender ID records, meaning the email likely came through an unauthorised mail server and could be junk.
By the end of the year, Microsoft will treat as failures cases where Sender ID records don't exist at all, increasing the likelihood those messages would be considered junk.
The Direct Marketing Association, the trade group for email and other marketers, lauded the move as "a necessary step to protect both corporate brands and consumer confidence," said Jerry Cerasale, senior vice-president for government relations.
Use of such systems, the association said, could help protect legitimate marketers from unauthorised use of their brands online.
Indeed, Spiezle said Sender ID has helped reduce the number of legitimate messages mislabelled spam. Email that passes the Sender ID test is given a slight positive boost in the filtering test, and for borderline cases it is enough to push the message to the non-junk inbox, Spiezle said.
But Spiezle acknowledged lingering concerns, including the disruption of mail-forwarding services that colleges and companies offer to alumni and subscribers.
Sender ID also could break "send to a friend" features in which someone clicks on a web link to pass an interesting item to someone else.
Spiezle said Microsoft is monitoring such cases.