Another prank app has hit the Cydia app store. Anonysend allows you to annoy your family and friends by sending fake semi-anonymous emails. I said "semi" anonymous because the emails are logged with your IP address. Meaning you shouldn't use it to prank your boss or harass an ex-girlfriend because it can be traced back to you. This app is for fun. It's not for abusing people you do not like.
The application is easy to use if you have a jailbroken iPhone: Just fill in a fake sender name, fake sender email, email of the person you want to prank, add a subject and hit send. Unlike the SpoofApp that allows you to fake your caller ID and voice, Anonysend is free to download and use.