This is a copy of a feature request from Link Mauve, lost after a server crash:
When I receive a direct message with a (picture) attachment, on XMPP I instead receive an empty message with just a @linkmauve mention. A better solution would be to use XHTML-IM or XEP-0385 or XEP-0447 (or even a fallback to the Conversations usage of XEP-0066) to embed the file as an attachment.