I went to battle with one medical supply place about a computer stamp and when they found out it was computerized, they said, Oh.. thats OK its just stamps that we cannot take.
Since then I have a standard paragraph that can be on a cover sheet that says (I am not in the office so am paraphrasing)
"We try to be green and paperless. The signature on these pages is computer generated NOT a stamp. As such, it is acceptable to HCFA. If it is not acceptable to you, please send the original and a SASE and I will sign and return them."
Only once has a company sent me a SASE.