Another fun one from Redmond is that OuthouseOutlook has the annoying tendency to "correct" -- to an — (mdash) for you. While more typographically pretty that doesn't really play nice with Getopt::Long or other such argument parsing when people naïve non-*NIX users (or even regular *NIX users) try and copy-and-paste the instructions you sent them straight into their shell.

Edit: In their defense it can be disabled, but that only helps you once you've done that.
Preferences > AutoCorrect > AutoFormat > "Dashes with n-dashes and m-dashes"