I found this interesting story in the Danger Room section of Wired (and not even in my custom “postal” feed). It’s interesting because they had to print hundreds of thousands of these pre-stamped envelopes to figure out when and where the one the suspect used was produced.
I also managed to get Danger Room‘s attention by calling out that a 6 3/4 envelope is not 6 3/4 inches wide. It’s 6 1/2 inches wide. See comments after the story for my post. A minor point, but it matters.