As a developer I don't write anything I submit anywhere, but I have had some experience with rejection letters when trying to publish my comics. Most publishers have a standard polite rejection that says the comic doesn't fit in any of their collections. But my favorite rejection letter was actually a checklist. It was a pretty devastating list of everything that could go wrong in a comic, but only one item was checked. It was a relief to see that while I didn't meet their criterias I still had most things right.

This was a relatively small publisher at the time and I suppose that they had started by writing a letter for every rejection, then found that many of these letters fell into similar categories, which allowed them to rationalize the process when they started getting more propositions.