We are using 1.9 RC1: This issue is caused by MS clients sending emails into the system with a ton of useless formatting style code embedded in the email. This overflows the "body" column in the ost_ticket_thread table. For a temporary solution, we've changed our structure for the "body" column from TEXT to LONGTEXT and it now handles the long email. This is resolved for us but thought others might like to know and it maybe an issue in previous versions as well - untested by us.
