EMail is just like snail mail. When it is sent you specify who you are sending the mail to, who you are and what you mail is about. You could send mail from the president if you wanted to and the only way to really get to where it came from is in the headers of the email and that still wont tell you much. Think of it like a letter.. you write it.. address it to someone.. then you can write any return address on that envelope you want and then drop it in the mailbox. Email works the same way essentially.
