Box 34567 is suspicious, at best. The current use of the po box 34567 is Ashland Chemical Company, A Division of Ashland Oil, Incorporated P. O. Box 34567 Houston - got this from a pretty direputable sight which seems to be helping the cause today.
http://www.usatoday.com/news/2004-02-14-bush-docs.htm
I found the above link on Google where these questionable memos were mentioned in a story in February 2004. There is a link for the memos but they are not there. Also, if you look at the link for records identified as "Miscellaneous" and see page 10/19, you will find the same address (Box and Zip Code) listed for the Commander of the 147th Fighter Group.