New user's questions re: local mail delivery

[folta@cs.UMD.EDU (Wayne Folta)]

I just got zmailer last week and I've been busily experimenting with it
on my desktop machine before putting it on our domain MXer. My main
questions have been about local mail delivery:

1. The stock crossbar claims that local delivery must use !-style
addressing, and that is absolutely incorrect (on a Sun, anyhow).
Unfortunately, I could not simply move the local case from the uucp
case to the smtp case, as @-style addresses cause my favorite local
delivery agent (procmail) great heartburn. So I had to roll my own
case for local that essentially did @-style addresses then sifted off
the @host part in the envelope. Is this the case for most people?

2. While experimenting with the local envelope address style, above,
I was procmail was refusing to deliver to foo@bar (where my local host is
bar), and I followed in the logs as delivery was tried, failed, then the
delivery went to /dev/null@bar. Is this normal? The mail disappeared
apparently without a trace. (No, Postmaster is not /dev/null.)

3. I'd like to bounce a warning message while still forwarding the
original (a cross between file and error). Has this been done?

4. Has anyone written a (say) perl script to transform scheduled zmailer
files into mqueued sendmail files and vice-versa? When I turn on zmailer
on the domain MXer, I'd like to have a fallback that would work even if mail
queued up.

5. You can evidently run multiple routers. Is this ever truly advantageous?
Is the load ever that large, and is there enough speed gain to be worth
it?

6. (I don't have the source in front of me here, so the names may not be
quite right, but...) The localnames database serves the same purpose as
the Cm line in sendmail.cf? And the domain variable serves the same
puspose as the Dm?

7. All of the transformations in the crossbar sifts are for the envelope
addresses, and the rewrite function is used for the message headers?

8. Has anyone done something where they add message header fields to
messages? (For example, "X-Postoffice-In:" and "X-Postoffice-out:"?)

Boy is zmailer impressive! I cannot wait to start using it for our domain.
Are there any warnings/tips that people might have for someone who will
be the first zmailer site in a large corporate network full of sendmailers?

   Wayne Folta