Nobody will share the content of the email, but it resulted in the unofficial blacklisting of the director(s)

An email was sent around town during the production of this A list movie about the movie’s director(s). It was sent to the most powerful people in the industry: agents, executives and producers alike. Nobody will share the content of the email, but a source confirms the content resulted in the unofficial blacklisting of the director(s) and several people linked or involved.