Hi BigArn,
Well, you should tell your friend to change his email in his account profile to whatever email he actually checks on a regular basis. The email that is listed on your account's profile is what we use for contacting players if they win a sweeps drawing or tournament, so having an email associated to his account that he cannot check means he could forfeit a prize due to non-response.
All he needs to do is go to his Account Profile and change the email to something he can check on a regular basis.
You should cancel the initial invite that you sent, wait for him to change his email and then send a new invitation at least 5 minutes after he's changed the email. That should send the invite to the updated email on his account.