I just got a message via WikiDot, that the sendmail links are failing. I corrected the ones on the milter-greylist/sendmail page.
It appears that sendmail.org basically no longer exists. Some of the docs (circa 2006) are available at:
https://www.sendmail.org/~ca/
The actual link to the open source version is here:
https://www.proofpoint.com/us/open-source-email-solution
Bill