opportunistic email encryption by the MTA (not MUA)

Fri Jan 15 19:34:25 UTC 2021

fyi, i was contacted by a clue holder from protonmail.  my guess was
correct.  they pointed me to the wkd section of

   https://protonmail.com/blog/security-updates-2019/

as i responded to them:

  i am definitely wondering how well it scales.  it adds query
  burden, often toward a server different than the smtp target.
  e.g. the wkd server could have sucky performance.

randy