The earlier post quotes an Iraq expert and former Clinton adviser, Laurie Mylroie, who says that the quality of the mailed spores was extraordinary and that they refused to stay on a microscope slide when scientists tried to examine them, due to their electrical charge and fineness. Interestingly, Miss Mylroie seems to think the anthrax came from Iraq.
OTOH the report above paints the anthrax material as somewhat crude.
I have no idea which of these accounts is more accurate. Either or both writers may have their own agenda.