[Mimedefang] Learning about to preserve information when relaying

[Steffen Kaiser]

Hello,

I'm merely trying verify that a particular message has been already 
scanned by a trusted mailserver, so I can rely on the correctness of 
certain header information, e.g. Spam status and absense of scannable 
virii.

My base is this:
http://lists.roaringpenguin.com/pipermail/mimedefang/2003-February/013267.html
and, of course, the man page.

So, I guess the security here is:

1) Because the key (a random value) is used by a particular host, I trust 
it.
2) The host would, if it sends me mail, either add such header anew or 
overwrite an existing one; or remove the header at all.
3) When spooling the message, the header is removed.

"The key should be kept confidential, but it's not disastrous if it leaks 
out." That's because an outsider cannot slipstream the correct header, 
because:

either the outsider cannot use the same IP than my trusted hosts or, if 
the mail gets relayed through one of the trusted ones, the key gets 
deleted or overwritten by the trusted host.

Did I understood it correctly??

A more "correct" (robust / secure) method would be to use certificates 
communicating between trusted hosts, right?

Bye,

-- 
Steffen Kaiser