Specifically the New York Post letter.
Look at the E
Clearly it was printed from bottom to top, every time.
No native born American ever would print an E that way, but it would be the natural way an Arabic printer would do it.
(Arabic script goes from right to left, from bottom to top).
Yes it could be a native trying to imitate the way an Arab would print, but would he be that clever?
By the way, the 3 letters and 3 envelopes were NOT all printed by the same person.
</i Note that there are some Americans with markedly different writing styles than most. See the following for an illustration, but railroad/Morse telegraphy has fallen pretty much into disuse since the midpoint of the 1950s [a pity; the beautiful cursive script was both highly readable and artistic in its own right] But I've also seen many Army message center pads with horrible hand-printing generally similar to that of the *anthrax letters*- from native English speakers. A well-studied graphologist would note major differences, I'm sure, though in the past I've worked with two documents examiners, and I ran some of this info past them, with two inconclusive and differing opinions about the handwriting in this case.
But check the following as an example of *industrial* or other influences on handwriting and penmanship, [and note the *rippled* lines/dashes- clearly the anthrax letter slinger is NOT an old-time railroad or Western Union *lightning slinger*] and other trades or subcultures also offer other differing examples of such specificality: