I have been playing around with the mailhandler module as I wanted to be able to post pictures to my site via email (my wife is expecting so it seemed like a good idea for the big day!)
I couldn't seem to find a ready made solution so I've been working on my own version by modifying mailhandler so it interacts with image. What happens now is that if I post a picture with my email / phone then the post is turned in to an image node, with thumbnails etc
You can see an example post that I've generated here.
I'm fairly new to Drupal so was wondering if I've used the "right" approach...
I have modified mailhandler itself so that during mailhandler_retrieve it looks for a jpeg, and if it finds one it extracts it.
During mailhandler_node_submit if a jpeg is there then it calls a processing routine just before doing node_validate.
The bit I'm not sure about, but is getting the job done, is that processing. The routine constructs an object, as if the file had come from an upload. It then calls image_validate but instead of passing a string it hands over the object. That seems to keep all the other modules happy, and they parse the object as a valid upload.
As a result image happily constructs thumbnails. If the processing routine was successful then the node type is left as an image. If validation failed the type is reverted to whatever was originally assumed. Control passes back to mailhandler_node_submit and the job is done.