Winmail.dat Viewer Pro Edition is a tool that allows you to view Winmail.dat files. Microsoft Exchange and older Microsoft Windows Outlook programs used to allow people to read, edit and send these types of files, but they are no longer used beyond the 2010 version of Microsoft Windows Outlook, which is why people must use apps such as this one to view them. You have to save the converted file in order to use it, which may not suit people who are using work computers or library computers where saving is not an option.