Whisperbot is a free service which helps you send email messages without disclosing your identity.If you want to send a simple message just visit whisperbot website type in your message and fill in the email ID of the recipient and click send. The other guy will get a link in his inbox, on clicking on the link the recipient can read your message. This way you can protect your identity and deliver the message at the same time.
Checkout whisperbot and send an anonymous message to a friend and see how it works out.

Cool service! thanks for the tip