RE: virus scanning

["Julian Mehnle" <lists@mehnle.net>]

Russell Coker wrote:
> On Sun, 15 Feb 2004 07:05, "Julian Mehnle" <lists@mehnle.net> wrote:
> > By that definition (which is of course as good as any), a receiving
> > mail server cannot reliably determine (if at all) whether an incoming
> > connection is a "direct" one, can it?  Except of course by
> > white-listing every single known-good mail server (hint SPF).
> 
> When mail from your favourite forwarding domain (such as @debian.org)
> comes in it's not direct, so you can configure your mail server with
> special case config options for the IP address of the Debian mail
> server. For all other messages you assume that the mail is direct.
> 
> There is no reason for someone to setup a /etc/aliases forwarding system
> pointing to you without your knowledge and/or consent.  You should know
> the IP address of every machine that will forward mail to you in such a
> manner. 

This is generally only true if the receiving mail server's admin has no users except himself.  If there are users with mail boxes on that machine, you cannot generally know from where they get redirected mail without asking all of them, which is usually not feasible.