4 ms·

There are privacy issues though. Take a known email address, run it through 100 sites, and find to find out what kind of sites the person uses.

• btilly 12y ago
  The point of the article is that you already can do this very easily - just try to sign up to each site.
  • Dylan16807 12y ago
    Which is an easily fixed flaw, when it comes to emails. Usernames, yeah, you're not going to keep those private. But sometimes account names are not the same as display names, and display names can be duplicates, while account names should be reasonably protected.
  • NoPiece 12y ago
    That's sometimes true, but not always. Two examples: a signup may have a captcha, so the cost of filling out the form to check for an email address is high, or something like a bank sign up, which requires additional info besides the email address (account number, SSN).
  • Akkuma 12y ago
    Gmail allows you to use email+whatever. A lot of sites actually support this and this means it becomes significantly harder to determine what sites you use as each email+whatever is considered unique.