Interestingly I just got the following email 5 times in quick succession:
Dear <not my name>,
Your npm package, <a pkg I've contributed to>, has been added to npm cdn:
https://npm-cdn.com/pkg/<pgk>/
npm cdn relieves the burden of publishing your code to
a CDN in addition to the npm registry. All you need to
do is add a link to https://npm-cdn.com/pkg/<pkg>/ to
your README file so that the users of <pkg> could embed
up-to-date version of your javascript files to their
web apps without additional steps..
Since I've only contributed a patch or two I presume they got my email address from scraping GitHub.