Editing Sender ID (section)

== Patents ==
 
The Sender ID proposal was the subject of controversy regarding [[licensing]] issues: [[Microsoft]] holds [[patent]]s<ref>{{cite mailing list |url=http://www.imc.org/ietf-mxcomp/mail-archive/msg04844.html |title=FW: Microsoft's Updated Statement about IPR Claimed in <draft-ietf-marid-core-03.txt> and <draft-ietf-marid-pra-00.txt> in Combination |mailing-list=IETF MARID List |access-date=2011-12-20 |url-status=dead |archive-url=https://web.archive.org/web/20120414184741/http://www.imc.org/ietf-mxcomp/mail-archive/msg04844.html |archive-date=2012-04-14 }}</ref><ref>{{Cite web|url=http://www.internetnews.com/dev-news/article.php/3409971/Exposed+Sender+ID+Patents+Up+Debate.htm|title=Exposed Sender ID Patents up Debate|date=20 September 2004}}</ref> on key parts of Sender ID and used to license those patents under terms that were not compatible with the [[GNU General Public License]] and which were considered problematic for [[free software]] [[implementation]]s in general. On October 23, 2006, Microsoft placed those patents under the [[Open Specification Promise]], which is compatible with some free and open source licenses, but not with the most recent version of the GPL license, version 3.x.{{Citation needed|date=March 2021}}