Peter Sewell was part of the Post Office Account Security Team at Fujitsu when East Yorkshire subpostmaster Lee Castleton faced his legal battle in 2007.
Lee Castleton was one of hundreds of sub-postmasters who were prosecuted over claims they were stealing from the Post Office - but the missing money was actually due to errors in the Horizon software, which was developed by Fujitsu.
Fujitsu manager labelled subpostmaster as nasty chap before High Court case kentonline.co.uk - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from kentonline.co.uk Daily Mail and Mail on Sunday newspapers.
Fujitsu manager Peter Sewell made the remarks about subpostmaster Lee Castleton in a 2006 email ahead of his legal case with the Post Office over apparent shortfalls