Test and learn how DMARC, SPF and DKIM work

HN hug of death? I sent an email to the address provided and over time, the page showed:

  Waiting for incoming email...  
  You don't have to write us an entire love letter :-). 
  Still waiting... 
  It's pretty quiet here... ¯\(°_o)/¯. 
  Waiting...  
  I'm giving up, reload the page to start over. (︶︹︶).

I've been very lucky overall to use Sendgrid for the majority of my email, so that DKIM is just a matter of setting up the CNAMEs they provide, but just had a situation where I had to set up OpenDKIM on a server running mailman to deal with the latest requirements from Yahoo and Google. (Apple also seems to be part of this enhanced enforcement, though never really mentioned.)