An old issue with some email apps is that we can view unread, all or read or filter such so it may appear empty.
Be sure you have the view of the sent folder set to "View All."
Windows 8 would be the same in this area.
my sent file is blank. I have reinstalled taken this to the store whrere it was purchased , techs could not fix.
if i install windows 8 does it have an email program included that hopefully will work .