Sign up and pick a username, let’s say you pick "joesmith". Now, any email address ending with …@joesmith.33mail.com will be forwarded to you. The next time you visit a website that asks for your email address, instead of giving them your real email address, just make one up especially for them.
For example, if the website is tribble.com, you might give firstname.lastname@example.org. Don’t worry, you don’t need to do anything else, we’ll create an alias automatically the first time they try to send you an email, and we’ll forward any emails they send to you.
Later, if tribble.com start to send you emails you don’t want, or even if they sell your email address to a spammer, just click on the link that we add to the top of every email we forward, we’ll kill their alias, andthey won’t bother you any more.