The dispute over Ceglia's emails came as Facebook and Ceglia battle over the exchange of evidence relating to the 2003 contract.
In a court hearing in Buffalo last month, Judge Leslie Foschio ordered Ceglia, 38, to give Facebook access to his web-based emails, which he has said he used to communicate with Zuckerberg in 2003 and 2004.
Zuckerberg has said he signed a contract with Ceglia in 2003 to do work on StreetFax, a business Ceglia was trying to start at the time. The contract made no reference to Facebook, which he started in 2004, according to Zuckerberg.
Facebook, which operates the biggest social-network website, has called Ceglia's claim to a share in the company a fraud on the court.
Closely held Facebook, based in Palo Alto, California, may be valued at US$71.2 billion ($84 billion), according to Sharespost.com, which tracks non-public companies.
At the Buffalo hearing, Gibson Dunn partner Orin Snyder told Foschio that Facebook's outside computer experts had found an image of the genuine contract signed by Zuckerberg on one of Ceglia's computers. It referred to StreetFax but made no mention of Facebook.
- BLOOMBERG