6 September 2004 Open source development group, the Apache Software Foundation (ASF), has rejected Microsoft’s Sender ID email validation proposal, claiming the licence terms of the anti-spam technology are too stringent.

In an open letter to the Internet Engineering Task Force (IETF), the ASF claimed that the software giant’s strict royalty-free licence agreement terms were a barrier to any organisation using Apache software wanting to implement Sender ID.

“We believe the current licence is generally incompatible with open source, contrary to the practice of open Internet standards, and specifically incompatible with the Apache Licence 2.0,” stated the letter.

Under the Sender ID patent terms, Microsoft can specify a licence that users have to agree to before they can use the code. Open source licences, however, state that anyone who receives the software under license may then become a contributor or distributor.

“We feel that dismissal of unspecified, pending patent claims recklessly shifts the risk and potential burden onto implementors,” added the ASF.

The Sender ID technology, which backers claim will largely eliminate spam by 2006, works by confirming the source of the email. It does this by cross-referencing the domain of the sender with the approved Internet protocol address on the publicly accessible Domain Name System (DNS).

The standard is the result of a merger between Caller ID from Microsoft and the open source Sender Policy Framework (SPF), proposed by Meng Wong, a notable open source software developer and founder of long-running email service provider Pobox.com.

However, to date, the standards have failed to gain traction, which could be due to the cost and effort for organisations to implement and administer them.