If you send any falsified emails from x10hosting, you will be permanently suspended.
If you upload any scripts that allow you to forge the "From" header as a prank, you will be permanently suspended.
http://x10hosting.com/aup
"* Forging of any TCP-IP packet header or any part of the header information in an e-mail or a newsgroup posting; or"
So, in short, if you forge the From header (which is the part most commonly forged in fake emails), we will permanently suspend you for it. Don't bother uploading any of the countless fakemail scripts that can forge that for you either; it gets suspended for "public abusable header-forging sendmail," which is permanent.