ewx | Learn The Words (Reply)

  From: ocado@ocado.com
  To: (me)
  Subject: Your receipt for today's Ocado delivery
  MIME-Version: 1.0
  Content-Type: multipart/alternative;
	  boundary="----=_Part_391555_1305389411.1337407149222"

That means “This message contains the same thing several times rendered in different ways”.

  ------=_Part_391555_1305389411.1337407149222
  Content-Type: text/plain; charset=us-ascii
  Content-Transfer-Encoding: 7bit

  Hi Mr Kettlewell,

  Your paperless receipt for today's Ocado delivery is attached to this email.

So far so good.

  ------=_Part_391555_1305389411.1337407149222
  Content-Type: text/html; charset=us-ascii
  Content-Transfer-Encoding: 7bit

  <html>
  <body bgcolor="#EFE9E5">

The same thing in HTML. No problem there.

  ------=_Part_391555_1305389411.1337407149222
  Content-Type: application/pdf; name=receipt.pdf
  Content-Transfer-Encoding: base64
  Content-Disposition: attachment; filename=receipt.pdf

  JVBERi0xLjQKJaqrrK0KNCAwIG9iago8PAovUHJvZHVjZXIgKEFwYWNoZSBGT1AgVmVyc2lvbiAw

Something completely different as a PDF. No, that makes no sense whatsoever.

Thunderbird displays the HTML part and offers the PDF as an attachment. That’s probably what they had in mind, but if you try and save the attachment it says it has zero length and gives up. That’s obviously a bug but it is trying to deal with a nonsensical situation.

Apple Mail displays only the PDF.

I don’t think this can have been tested very thoroughly…