Little fun thing I found today, both Gmail and Outlook offer the possibility of having dynamic email aliases.
As an example, assume your email address would be “email@example.com” or “firstname.lastname@example.org”.
If you add a + to your existing address (i.e. foo) it is possible to create an ad-hoc alias that would send the email to the registered email.
So email@example.com would send it to firstname.lastname@example.org.
It is then easy to create rules in your email inbox to determine the origin of the email and if it would be spam, you can easily know if your email address has been sold to spammers by the website your gave your email to.