Cormac Lawler said:
Secondly, if there is a way of multiparting this message with text and html - great! Let's do it. (How?)
Not sure, but I suspect that some mailers, such as Outlook, may do this by default.
Thirdly, that one pixel image used by spammers is surely inserted into the email by the spammers, no? I mean, we're not going to be doing that, right?
Absolutely not. But it's a good reason not to interpret html emails if it is feasible to ignore them (for instance, they're definitely not from your boss, a client, or your mother) or read a text alternative. Spammers often send html-only because if you read the text version they don't get any feedback.