You might know of this solution: in GMail, you can write your email: myemail@gmail.com (for example) in the following ways:
- my.email@gmail.com
- m.y.e.m.a.i.l@gmail.com
- my.ema.il@gmail.com
- myemail+label1@gmail.com
- myemail+label2@gmail.com
- mye.m.a.i.l+label1@gmail.com
… And so on, pretty much any combination of dots and labels.
You might be tempted to use email+site@gmail.com for each web site you register with.
The trouble is, the +label solution is pretty much a known fact, and if someone sells a database of emails, including yours, the entity who buys the database with your email in it might automatically remove all the dots and +labels from GMail addresses.
I still think that you should be using +website label to each site you register with, so that you may know if they sell your email, I’m just saying the solution is not bulletproof.