Norwegian language is very influenced by danish and oldfashioned norwegian is similar to danish.
But I don't think danish language would use the word "som" nor would they use "at faa" in this sentence: Det billede som det sikkert glæder dig mest at faa.
Danish would write "der" and "modtage" instead: Det billede der glæder dig mæst at modtage.
My danish is not good, but I am norwegian and have read some oldfashioned norwegian. I still think this is oldfashioned norwegian.
Does the photos themself have any buildings, uniforms etc that might give us some clues to their origin?