In reply to The Lemming:
> Nice tip to know though.
ah someone is taking the piss.
As a more helpful hint for personal use you can often insert in punctuation without it changing the email.
So for example with gmail the . is ignored. Which means you can use it in an email address on a site to uniquely identify them
L.emmibondageloverwhiprodent@gmail.com can be UKC
Le.mmibondageloverwhiprodent@gmail.com can be UKB
Likewise plus can be used in the same manner but to append entire words.
Lemmibondageloverwhiprodent+fred@gmail.com
would still go to your main email address. However that is a tad less subtle in use.