Does postie not resize any more? Old postie ran (if properly configured) ImageMagick (http://www.blackrosetech.com/gessel/2008/08/07/fixing-imagemagick-resize-in-postie) and put resized thumbnails in /wp-photos/thumb.(filename).jpg.
Current postie seems to reference the original image and resizes in the browser (true?). If so, then page loads could be painfully slow as large images are downloaded and scaled.
That postie created thumbnails was one of the most useful features.