From the Mailinator FAQ:

Mailinator is a different kind of email service. The biggest difference is that you don't need to sign up

Mailinator email inbox can be read by anyone. There is no real security here. Mailinator has strict rules about what kind of email it receives. Plain text is best, html is filtered. Images, attachments, and fancy stuff are simply stripped away.

Logins

For "free with signup" websites you can use the account:

iths@mailinator.com / 8uw!iths

Valid for: