Enjoyment: Quirky little submission, which i enjoyed my time spent with it.
Gameplay: Solid puzzle type game, would have love to see more than the destination as neccessary to solve part, but you already mentioned that in the description. I did not complete the complete handbook, so I'm not certain for sure, but i guess thats the "end of game"-condition ?
Innovation: Very refreshing go at the genre, felt very crossword-ish, in a sense the more mysteries/fields were solved the easier the rest gets.
Theme: Solid interpretation of the theme in the intergalactic mail office!
Visuals: The intro was nicely done - nearly missed it, as for my first playthrough it was just the solid color screen - quite liked the individual species. Stylized GUI to fit the rest would be a nice addition.
Audio: Strong / Solid choice of music - the loop wasn't getting annoying over the time.