On 9/2/2013 2:40 PM, R. David Murray wrote:
I'm still not understanding how the text/plain part *refers* to the
related parts.
I don't think the text/plain part can refer to the related parts, but, like you, am willing to be educated if there is a way; but while the text/html may be able to if things like cid: URIs can reach up a level in a given MUA, the text/plain would be left with the additional parts being attachments, methinks. This is less interesting than the technique Apple Mail uses, but more interesting than not even seeing the attached pictures.

MUAs tend to be able to display what they produce themselves, but I have situations where they don't handle what other MUAs produce.

One nice thing about this email6 toolkit might be the ability to produce, more easily than before, a variety of MIME combinations to exercise and test a variety of MUAs. While perhaps most of them have been tested with some obviously standard MIME combinations, I suspect most of them will produce strange results with combinations that are out of the ordinary.