I have one computer that lists messages in the sent folder going back a year or more. The sent folder listing shows different files sizes as if they contain data. Clicking on recent sent messages displays there content in the preview pane. For messages older than 6/19/14 the messages display as either completely blank, or in some cases there may be a block of random characters. My first thought was that the encoding changed and the new Thunderbird didn't know how to display the old messages. Was there an update around the middle of June that might have caused this? Any other ideas? I have other computers running Thunderbird that don't seem to have this problem. This is a Windows 7 system that was purchased 3 years ago. Thunderbird was installed shortly after that. This is the first time we have noticed any problems.