Yakov Shafranovich <research(_at_)solidmatrix(_dot_)com> writes:
Even if there isn't enough time for the lawyers to get back to us,
nevertheless an alternative draft without IPR problems should be
preferred according to RFC 3668, section 8 unless it is superior:
" In general, IETF working groups prefer technologies with no known IPR
claims or, for technologies with claims against them, an offer of
royalty-free licensing. But IETF working groups have the discretion
to adopt technology with a commitment of fair and non-discriminatory
terms, or even with no licensing commitment, if they feel that this
technology is superior enough to alternatives with fewer IPR claims
or free licensing to outweigh the potential cost of the licenses.
"
While IANAL, it could be argued that the Microsoft Sender-ID licence
is not non-discriminatory as it (according to many people here,
including lawyers) discriminates against open-source implementations.