I recently emailed the author of an online short story that I read, asking permission to use his story as a basis for a screenplay and eventually, a short film. He emailed me back, giving me a personal statement declaring that he has given me permission to adapt the story into a screenplay and film.

I had planned on entering this film into a festival. In order to prove that I have obtained all llegal rights to use this story, would I just print out a copy of the email history -- my original email, and his response that gave me permission? Do I need his signature?

A signed release would be best! But you should be fine. The problem would be if he sold the story to a publisher or another filmmaker then whoever had the rights could put the kibosh on your film.

Although if it's a straight up student film with little plans of distribution than ultimatly it's not an issue. But it's never to early to be legit.