Thanks Wayne, Chris and Matthew for your great thread.  I've started another thread asking about the minimum vm resources for a system such as you are discussing.  

Chris has some sage advice as always, 20 years ago Chris and I were exchanging email almost daily regarding Dnews and Surgemail...  Netwin provided top-notch service and support... if all my vendors were like that, I would still be in the ISP business.

In reading Matthew's post, I realize hadn't even considered IP address reputation...  Which is pretty stupid, given how many years I have spent dealing with IP reputation issues.  So thanks for the reality check, Matthew!  When I last had to deal with reputation mitigation, it was when working for a large Hospital with 15K+ users, with a penchant for responding to every phishing attack (Doctors are the stupidest people when it comes to properly dealing with phishermen).  Back then it was still in the IPv4-only days, and most filtering was done on the bounds of a single IP address.  It makes perfect sense that for ipv6, filtering is done on a /64.

Matthew, were you able to get a /64 allocation from anyone?  What does your service end up costing?

I suppose you only need the main server on IP's with a good reputation, and you can mirror to anything as a secondary...

It sounds like it might make sense for a group of us to create a entity to get an small /48 ARIN block, and share it at a mutually agreeable hosting provider...  Though that also sounds like it could be a pain if the group is more than 2 to 4 people...  But assuming it would work out, there would be plenty of /64's in there to give each member a block of them.  Assuming, of course, that this is better than just going with a host that hands out /64's.  

So far it is sounding like I might be able to use a cheap provider for the non-sending mirror, but I will need a good provider for the clean-reputation IP block.

I have public IP's at work in a lab I manage, but I didn't really want to do this at work.  I have a former ISP partner out there I could try to call in a favor, and have him let me co-locate a server...  But he's gotten caught up in some of the mess related to my current email issues, and it is tempting to just make a clean break, as he wants to stop hosting email all together.  Perhaps he might be interested in a trade of some kind...  But before I do something like that I want to find out more about Matthews experience.

Thanks guys!!

George