The description of the debian-amd64 list is "Debian port to AMD64 Porting Debian to AMD x86-64 architecture."
so unless you're involved in Debian's amd64 porting effort I'd say you probably don't have any reason to post to that list. I remember a while back mostly 32bit users were on this list when amd64 was new. Then I think you were supposed to be on the amd64 list. Not any longer...... Thanks for pointing this out. Michael Fothergill