A successful transmission is documented by a transmission report. Depending on the settings in the preferences, the transmission report is displayed as a PDF file, either always or only upon request. In addition, you can also define whether a list of the individual items contained in the file should be displayed at the end of the transmission report. You can find additional information about the various setting options in chapter Preferences - File transfers - Print settings.
The transmission report is also opened by a double click on the respective line under Sent Files or by clicking on Print in the context menu.