On Mon, Aug 23, 2004 at 07:01:00PM -0700,
Harry Katz <hkatz(_at_)exchange(_dot_)microsoft(_dot_)com> wrote
a message of 457 lines which said:
For the convenience of the working group, attached is the full text
of the FAQ.
Reading the FAQ:
A7: [...] we believe you can distribute your implementation under
many open source software licenses, [...] Microsoft has not been
made aware of any specific incompatibilities between any of the
licenses used to distribute Sendmail, Postfix, or Qmail with
Microsoft's royalty-free patent license.
There is a big free software licence missing, the GPL (none of the MTA
mentioned uses the GPL. Exim, which does, is not mentioned and I
assume it is not a coincidence).
Taking this into account and reading Eric Allman analysis
(http://www.imc.org/ietf-mxcomp/mail-archive/msg03500.html), it seems
the most common free software licence, the GPL, is incompatible with
Microsoft licence on SenderID.