Thanks for all your input guys.
I did some further research and went as far as contacting some computer forensic experts via email, and explained the story to them. These are the kind of guys that are used to verify authenticity of this kinf of stuff for any legal case where electronic documentation must be authenticated.
I was surprised to hear back from 4 different firms. 2 of them said that so long as the 'received' email still sits on the server, and can be proven via hard and digital copy presented as evidence in court, it's generally admissible. The cost of providing legally admissible authentication paperwork would excede the value of the claim, and therefore the judge would simply rule in favor of the plantiff provided there is substantial and convincing documentation. A couple of the other repsonses offered to provide the legal authentication with fees ranging from a few hundred to a few thousand dollars (right in the ballpark of the claim). Also, nowadays, if need be, a judge may provide access to a computer to pull up the email if necessary. It probably wouldn't get that far anyway.
Therefore, I have advised my friend simply to retain file copies of these emails on disk as well as hard (printout) copies and to bring them to court with him. He should probably bring in his laptop too, just in case they have WiFi and he is able to pull up the email directly on his computer.