I am not sure what it is with road runner, but I've seen them turn down perfectly valid E-mail from valid ISPs as spam. Not flag it as spam, but return to it saying it was rejected with not enough authorization, and little else.
IMHO, Road Runner is a decent service for getting your Internet connection, but if you want decent E-mail, go with a paid provider that provides solid service. I've had good luck with Yahoo's paid services, and there is of course Google Email.
Anyway, I'd turn off spam filters, try it again, and then look into calling his ISP to see what is up. For him not to be recieving mail is either an error on their end, or your friend can't remember his own e-mail address.