For example, if I get an email addressed to [email protected] from a mortgage lender, and I only used this email address with a web store that sold tropical fruit, I now know where the mortgage lender got their email from. Plus addressing is a good mechanism for email sorting and some email misuse detection, but because it’s such a well-known technique at this point, it doesn’t take a genius to figure out that [email protected] is actually [email protected] , and a lot of online marketers and other individuals that are interested in collecting email addresses caught on.