The emaillog.txt file is a log file which is only generated while your scanning service is in debug mode, so it is safe to remove this file. Seeing as the file is quite large, do make sure that your service is no longer in debug mode as this is known to cause exponential growth of your log files.
If needed, you can revert your service out of debug mode by opening ConfigEditor.exe under under Program Files (x86)\Lansweeper\Tools, clicking the Reset to default button and clicking Save configs and restart service at the bottom.
