The personal email account of former New York Attorney General Eric Schneiderman is the subject of the latest dispute in the state’s lawsuit against Exxon Mobil, which is accused of misleading investors about the risk posed to its business by climate change regulations.

Attorneys for Exxon Mobil claimed in a new letter to Manhattan Supreme Court Justice Barry Ostrager that Schneiderman used his personal email account to conduct official business related to his office’s investigation into the company.