Time was, you could open up an email in your favourite email client and read it without too many concerns about how that email was constructed. But times change, or so it would seem...

My pain of the moment is the abuse of the "multipart/alternative" version of multi-type emails. Specifically the almost complete absence of valid textual-alternatives in these emails.

Just to recap - RFC 2046 section 5.1.4 (Alternative Subtype) states that:

5.1.4. Alternative Subtype The "multipart/alternative" type is syntactically identical to "multipart/mixed", but the semantics are different. In particular, each of the body parts is an "alternative" version of the same information. Systems should recognize that the content of the various parts are interchangeable. Systems should choose the "best" type based on the local environment and references, in some cases even through user interaction. As with "multipart/mixed", the order of body parts is significant. In this case, the alternatives appear in an order of increasing faithfulness to the original content. In general, the best choice is the LAST part of a type supported by the recipient ...

I've long since given up configuring my email client (mutt) to indicate that text is the preferred type. The number of emails that arrive claiming to have "multipart/alternative" sections but which contain only "Your email client cannot read this email" in the text section finally meant that I had to process the HTML email sections instead.

I've almost grudgingly accepted that as just the way it is - but an email I received today tipped the scales. It read (start to finish):

[emailer_top] [emailer_bottom]

I checked the email - nothing but that and a PDF attached. I tried viewing the email with a different client and finally realised that the entire text of the email was embedded in images!

The email was a "multipart/alternative" - but the text section read:

This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible.

Superb...

So this is just a plea into the void - when anyone receives such emails contact the sender and tell them what's wrong. If you know that you or your organisation are responsible for such emails being sent - STOP DOING IT. (please!)