I will have to say "Big Fan" is right, Jammie. I emailed the myspace persona also. However, in the process I also contacted Papa Joe Entertainment and Productions (Jessica's Dad's Company), Here is a copy of the email

Dear Mr. Simpson (Joe),

For the past few weeks I have had small conversations with your eldest daughter, or so I think it is your daughter, over myspace.com. Little questions here and there nothing too serious. I know it is awkward that a person/stranger, who also is a MySpace person is contacting you. But I want to be sure that who I am talking to is the “real deal” and not someone who is lying and falsifying their identity by portraying as the celebrity and as your daughter. I would like to include the information that gives reference to your eldest and confirm with you that the person is her.

The addresses I have had contact with are.
http://www.myspace.com/sweetjessicakisses
http://www.myspace.com/jessica80simpson

Sincerely

And here is the response.
From: [mailto:erin@jtentertainment.net]
Sent: Sunday, February 03, 2008 2:18 PM
To:
Subject: Re: Papa Joe Records Inquiry

I can assure you that you are not speaking to jessica. She does not have a myspace account. Thank you for bringing this to our attention.