Pastebin

 37 \usepackage{eso-pic, pdfpages}%, lastpage}
 38 \AddToShipoutPicture{
 39   \setlength\unitlength{1mm}
 40   \put(0,257){
 41     \includegraphics[width=210mm]{so-letter-header.png}
 42   }
 43 }
 44 \AddToShipoutPicture{
 45   \setlength\unitlength{1mm}
 46   \put(0,0){
 47     \includegraphics[width=210mm]{so-letter-footer.png}
 48   }
 49 }