I've been using this for a little while now and it works great, as advertised.
Hate keeping multiple email addresses just so you have one to insert when a website requires a valid email address for registration so they can send you a confirmation note with your password or a link to validate? Me, too.
Make up one, any email address prefix, and send it to @mailinator.com . Then go to mailinator.com and enter that address you made up, your email will be there for you. You can then fetch the password, or click on their validation link, whatever you want. Emails are deleted after a few hours but I always want that info immediately anyway.
They will also autogenerate one for you that you can have ahead of the need, but I'm unclear on why that'd be a benefit.
It works for me. mailinator.com