I've noticed no particular pattern to the images that IA rates "unscannable" - it can anything from a simple JPEG in a sig up to monstrous embeddings in multiple attachments, the appliance can be quiet or relatively busy, and the problem images themselves can be very simple. The only common element that I can think of is that none of the samples I've actually looked at could be deemed "inappropriate" in any way.
The Advanced Guide really only has the basics on IA - is there another source of information I should be looking at before hassling support?
Alternatively, are unscannables something that I should just expect and deal with when using IA? If so, does the forum tend to drop, notify or simply wait for end-user bleatings?
Our Asyncos version is 6.40-273 on a C150, if that's relevant.