Why are email that I import with a DAT file incomplete?
When you choose to import natives with a loadfile you have two options
1. Use the metadata in the loadfile.
2. Use the metadata extracted from the natives.
If you choose to have the metadata in the loadfile Summation will attempt to build a view for you of the email in the viewer based on the metadata that was mapped. If you don't map a field, to Body for instance the Body will be blank. If you have the native, you can check the process files to extract metadata box and your loadfile metadata will be ignored.
Importing natives have different options and behaviors for handling metadata.