The MS Outlook font only has a small number of actual characters (12, including a blank space) that are used as icons within the Outlook program. It is not designed to be used as an actual typeface: http://s16.postimg.org/ii8ov0dad/8_Tuc_B.png
The “boxes” are simply undefined characters within a font. I hope it will assist you in resolving issues.
Thanks & Regards