But will it work???
Well there you go.
Click the thumbnail to increase size, click full size image to return to thumbnail.
Ian's original image (his email attachment) is a .png file (size 1.842MB) which exceeded the allowable attachment size, hence the error message that Ian reported.
info - What is a PNG file? Portable Network Graphics files (PNGs) are compressible and like JPEGS, can handle 16 million colors. They're mostly used for web graphics, logos, charts, and illustrations, rather than high-quality photographs, because they take up more storage space than JPEGs.
.png files are typically larger (by a factor of 5-8 times) than .jpg files.
Moral of the story - stay away from .png files - use .jpg instead.
I had to tweak the Message Board Attachment settings to make it work properly - more adjustment may be required in the future.