is this e-mail Legit?

No,That's nothing...
There's a script to modify your domain =)

its not a "script"
its simply exploiting an obvious and unfixable flaw in smtp and pop3 email servers. when you send a certain address an email, your email server also sends the email address that sends the mail, but it does not require the password. basically, you tell your email server you are someone you arent. its your server, you can do whatever u like with it.