Microsoft's earlier attempts at a specification for Sender ID, the technology which is used for verifying the authenticity of e-mail with Internet Protocol records, was not exactly received well by the security expert community. Last month, the IETF shut down the working group that was charged with building consensus for Sender ID and turning it into an industry standard.

Microsoft have now revised their specification for the antispam technology, in order that the concerns raised are addressed. Many changes have been made, not just to the specification but to the patent documents; Microsoft removed language in its pending patents for SenderID that could have included claims to Sender Permitted From, or SPF, a widely used system for e-mail authentication. Microsoft also revised Sender ID by making it backward-compatible with 100,000-plus SPF records already published.

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