C.<p>Something happens to me occasionally, and I don&#39;t know where to put it in the ridiculous - infuriating - preposterous feelingspace. It happened again today.</p><p>Backstory: I&#39;m an email geek, who has been running mail servers for three decades, and who has written a lot of mail-handling software. I&#39;ve worked as a consultant on email systems for companies large and small.</p><p>When you run your own mailservers, have deep experience with MTAs, and are a bit of a privacy nut, you might have a tendency to want to know exactly who does what with your email address when you give it to them. For most people, this desire is just a dream; it&#39;s not possible with their email system.</p><p>Thanks to a technique semi-related to <a href="https://mindly.social/tags/VERP" class="mention hashtag" rel="tag">#<span>VERP</span></a> - variable envelope return-path, a mailing list feature with the qmail MTA - it&#39;s possible for email geeks. Basically the idea is that you give a different email address to everyone you deal with, and keep track of who you gave it too. Then, when you receive email, you can tell from the address the email was delivered *to* - one of your many addresses - where they got your address from.</p><p>Example:</p><p>Say I own the `example.net` domain. I arrange for all email to that domain to come to me.</p><p>I decide to order something online from <a href="https://mindly.social/tags/CrappyTire" class="mention hashtag" rel="tag">#<span>CrappyTire</span></a> (ask a Canadian). When the Crappy Tire website asks for my email address, I type in &quot;crappytire@example.net&quot;.</p><p>1/x</p><p><a href="https://mindly.social/tags/FeelingSpace" class="mention hashtag" rel="tag">#<span>FeelingSpace</span></a> <a href="https://mindly.social/tags/ColourSpace" class="mention hashtag" rel="tag">#<span>ColourSpace</span></a> <a href="https://mindly.social/tags/email" class="mention hashtag" rel="tag">#<span>email</span></a> <a href="https://mindly.social/tags/tracking" class="mention hashtag" rel="tag">#<span>tracking</span></a> <a href="https://mindly.social/tags/spam" class="mention hashtag" rel="tag">#<span>spam</span></a> <a href="https://mindly.social/tags/MTA" class="mention hashtag" rel="tag">#<span>MTA</span></a></p>