Malware spam: "Image data has been attached to this email." / "Scanned image"

This spam is presumably meant to have a malicious attachment, but all the samples I have seen are malformed:

From:    support398@victimdomain.tld
Date:    18 July 2016 at 16:22
Subject:    Scanned image

--+-+-+-MGCS-+-+-+
Content-Type: text/plain; charset=iso-8859-1
Content-Transfer-Encoding: Quoted-Printable
Content-X-CIAJWNETFAX: IGNORE

Image data has been attached to this email.



--+-+-+-MGCS-+-+-+
Content-Type: application/vnd.ms-word.document.macroEnabled.12; name="18-07-2016_rndnum(4,9)}}.docm"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="18-07-2016_rndnum(4,9)}}.docm"
Content-Description: 18-07-2016_rndnum(4,9)}}.docm

UEsDBBQABgAIAAAAIQB+OOx6hwEAAK0FAAATAAgCW0NvbnRlbnRfVHlwZXNdLnhtbCCiBAIo
oAACAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAC0lM9OwkAQxu8mvkOzV9MueDDGUDgIHpVE
[snip]

The spam appears to come from within the victim's own domain (but doesn't). In case you don't recognise all those random letters, that's what an email attachment looks like.. but something has gone badly wrong with this spam run. I haven't analysed the payload, but it is likely to be Locky ransomware as found here.