[gentoo-user] encrypted email (gentoo-windows)

[James]

Hello,

Background:
I use Thunderbird as my email client,
but the mail servers of another (my isp).
What I want is an email setup that interoperates
with encrypted emails from various unix and 
windows based servers. (maybe dreaming here?)

So I'm research on interoperability
of eningmail, pgp, and such, but everything
I find is dated; citatiions appreciated.

Q1. Is there a method that will all me to set
up my email client(s) using various mail servers
as their smtp_host that start out with really good
encryption/dig-signatures and then auto fall back
down to lesser secure option with the last one
being ordinary email services?

Q2 Windows....
I'm not too versed in Windows. I try to avoid all
things windows. Unfortunately most of my activity
(emails etc) is with folks that like BG and the Redmonds.....
So what I thinking is there are few (MS)sites that actually
have some sort of auto-negotiations scheme to try for the
very best security between email servers (nix-doz) and then
fall back down the scale to a circa RFC822 type
of negotiated arrangement. But most MS sites are
brain-dead on there mail server and try hard to 
not be interoperable with *nix as with all things
Redmond?

At the very least, maybe there is a tool(script) to
run that will ferret out the offered secure email exchange
options with a given mail server, categorize them, and at
least use secure email correspondences with those mail servers
that have been flushed out? Dunno. I'd settle for secure
email with the majority of sites I regularly exchange
emails with.

It's been a while since I set up a mail server, but, 
if that (postfix) is what I need to do, then just tell 
how (overview) the packages you'd use, or is this part of postfix?


Q3 
Any documents, comments, or guidance is most welcome.


James