I do find it odd to delete the headers and thus lose information (making impossible to reconstruct the original message), but that is what SpamAssassin itself does. Munging the header names as you suggest (with X-Old- or whatever) to preserve them makes more sense to me.
qpsmtpd != SpamAssassin.
Just because your friend jumps off a bridge, will you too?
-R (watching the water go by)
