receiving (postfix) emails via (rails) http; using file upload (-F) for less verbose Rails log (otherwise use --data-urlencode)

diy.cloudmailin.bash

#!/bin/bash

MAILFILE=/tmp/mail.$$
CURLFILE=/tmp/mail.$$.curl
cat > $MAILFILE
curl -i -F message=@$MAILFILE "http://localhost/incoming_messages" > $CURLFILE
if grep 'HTTP/1.1 204 No Content' $CURLFILE
then
  rm -f $CURLFILE $MAILFILE
fi

incoming_messages_controller.rb

class IncomingMessagesController < ApplicationController
  def create
    raw = params[:message].respond_to?(:read) && params[:message].read || params[:message]
    mail = Mail.new(raw)
    # do stuff
    head(:no_content) # bash script will detect 204 and rm -rf tmp files
  end
end

postfix.main.cf

mailbox_command = /somewhere/diy.cloudmailin.bash

What happens if curl fails? Does postfix re-queue?