List Fields will by default operate in easy-mode, and thus automatically convert all MIME fields into richtext. This means that you won't see the real MIME fields since the programming interface on a low level convert the MIME fields into richtext before clients, such as List Fields, can see them.
Below you see how a MIME message looks in the Lotus Notes client:
And now we take a look at this document in List Fields, in easy-mode:
In the screenshot above the Body field has been selected in the Field List Area, and thus it's content are shown in the Output Area. Note that we only have one Body field, and that the content obviously is of type richtext. Also note that the imbedded images from the MIME message are stripped out and replaced with [IMAGE]. Lotus Notes has aided the programmer by making it much easier to access the content of the message, as opposed to accessing the different MIME parts individually. The result is however sometimes not completely satisfactory.
Also note that you can see the status of the MIME processing by clicking on the MIME button in the statusbar: