Existing anti-spam filters can easily be tuned to support SPF, Wong said. Anti-spam technology providers, such as CipherTrust Inc., InboxCop Inc. and Sophos plcs ActiveState division, have thrown their support behind SPF. CipherTrust in fact announced Thursday that it has incorporated SPF into its IronMail anti-spam appliance, using the SPF domain registry as a data point in IronMails Enterprise Spam Profiler correlation engine. CipherTrusts FirstAct service will provide the companys customers with automatic updates from the SPF registry on an ongoing basis, as well as assistance in registering their more than 1,500 domains with SPF, said CipherTrust officials, in Atlanta.SPF would be free and voluntary, according to Wong, with its effectiveness dependent on the number of domain holders that register their sender IP addresses. Nearly 7,000 domain holders have registered their IP addresses at the SMTP+SPF Web site, including American Online Inc., SAP AG, Mail.com and the World Wide Web Consortium (W3C). Support for modifying SMTP is growing within the e-mail industry. "The only way to stop spam on a permanent basis is to change the SMTP protocol," said John Davies, CEO of e-mail server software developer Rockliffe Inc. "If SMTP protocols are enhanced to provide the capability to validate the sending server, it becomes impossible for spammers to send spam anonymously." Davies said Rockliffe is looking to support SPF in a future release of its Mailsite e-mail server product. Mailsite currently supports the Simple Authentication and Security Layer (SASL) with SMTP, which SPF also uses at the MTA level. While the SPF work began last June, Wong said that efforts to modify SMTP have been under way since 1998. There are other draft initiatives in the works to validate return e-mail addresses including Designated Mailer Protocol (DMP) and Reverse MX. Wong described SPF as a superset of DMP and Reverse MX and said acceptance of any one of the three will reduce spam. "SPF is certainly not original, but were beginning to shepherd people to use it," said Wong. "Our customers say we have to do something about spam, so this is what were doing." Next page: SMTP flaws need fixing.
"SPF works pretty well with everything else," said Wong. "Were not looking to be a competitor to anything else."