Outlook 2000 RTF Attachments Turned to D

I am using Outlook 2000 and Word as the editor to send 1-1/2 page text in body of e-mail and attaching a .rtf (Rich-Text-File) formatted file that is a word form for ordering our publications. Most of the recipients on the receiving end get the rtf form as a very large .dat file and they can not read, print or display the file. In many of the receiving PC’s it causes them to crash for out of memory or lock-up problems