Earlier quoted context omitted.
I know at least one person who has their own personal family domain set up so that his family members can just create new email addresses specific to the vendor when shopping online (for example, 'amazon@familyrobinson.com' and 'bestbuy@familyrobinson.com' ). Then all their shopping emails just get routed to his domain. Being able to track which company leaked or sold an email address seems like another benefit in ad…
Gmail has this feature baked in. Append a + sign to the username and then append any string you want, ie. username+ycombinator@gmail.com. It will forward these mails to your regular email address. I started doing this for the exact same reason as mentioned above, but you can obviously do more than just creating honeypots. Also you have to ignore the fact that it's Google...
Usually soluble, but irritating.