147 Strangers Were Sending Mail as My Domain and I Had No Idea
For years I had no idea who was sending email as justplainsimple.com. Not a vague sense. No idea at all. I knew the theory. SPF says which servers may send for you. DKIM signs your mail so it survives a forward. DMARC ties those to the domain in the From: header a human actually reads, and tells receivers what to do when neither lines up. I have explained this to other people. I had implemented none of it on my own domain. ...