E-mail anonymously

If you ever want to send someone an anonymous e-mail or SMS, Sharpmail is the service for you.   Sharpmail allows you to put in your own return e-mail address on the letter. Perhaps you wish to e-mail a co-worker but don't want others finding out who sent the message.

Be warned however, you are not allowed to use the service to send abusive mail or spam.  However, I don't know how you couldn't just set up another free account.