When Stewart insisted they said they looked at the images
with Microsoft Paint and saw that the resolution was 96DPI, so not good enough for the publication!!
It looks like these people are still living in the 1980's.
They may or may not have a point, but looking at the DPI tag in the file is a totally stupid way to tell if the file is suitable or not. You need to look at the pixel dimensions and figure out the print PPI from the pixel count and intended print size. THe file PPI tag is meaningless; you can set a 400 pixel web JPEG to 400PPI and a full-res 1Ds-MkII file to 5 PPI, but that won't make the web JPEG ook better than the 1Ds-MkII shot.