There's a better-than-fair possibility its a file created on a PDA usin' the PALM operatin' system. If so, ArcSoft's
3D Text Factory (15 day trial) should open it.
However, unless I knew who sent it to me, and knew that person meant to and did in fact send it to me, I knew what it was supposed to be, and it scanned clean for infection, I wouldn't think it wise to try to open it.