You have to register on an unreliable site or forum that you will flood with advertising it’s spam? Do you need to receive a message in a relatively short time just to activate an account?
Nothing easier, thanks to email temporenee which expire after a short time and do not need to be registered!
One of the best and most useful web services you can think of can be found on the website www.spaml.com (to always have in the bookmarks).
The site in question generates a temporary email as soon as you visit the page and automatically updates itself thanks to AJAX technology to check for new messages.
In clipboard you will find the temporary email to communicate, so as to easily bring it pasted on a site and you can possibly customize it to use the your name instead of a causal number (in the proposed example there is firstname.lastname@example.org, initially the email was email@example.com).
Once you have received the email, you can close the page without worrying about anything at all. To try!