The answer I'm about to give is not likely to be very enlightening. That particular message, when parsed by the Ruby mail gem, has no attachments.
https://whimsy.apache.org/secretary/workbench/201811/f19c4032c4/ If you look at the raw version of the message, you will see boundary="----=_NextPart_5BE02944_0A60A880_294A6503". If you look a few lines later, you will see "------=_NextPart_5BE02944_0A60A880_294A6503". Note that the boundary has FOUR leading dashes, and the line itself has SIX. The mail gem does not consider this a match, so it doesn't identify any attachments. I don't know enough about the relevant RFCs to know whether this is a malformed message (which some mail readers may compensate for), or if it is RFC compliant message that isn't parsed correctly by the mail gem. - Sam Ruby
