mail confusion

[Les Mikesell]

On Tue, 2005-11-08 at 23:12, Jay Moore wrote:
> > 
> > No, the only thing you need it fix is if you want to accept mail
> > on addresses other than 127.0.0.1 and sendmail's idea of your
> > hostname if it isn't what you want as a return address.
> 
> But that's just it - I *don't* want to accept mail on addresses other
> than lo (127.0.0.1). On this machine, I get my mail from a "real" (i.e.
> Internet DNS-resolvable) server via POP3. I only want to send mail from
> this host

Then you just have to supply a usable 'From: ' header on the message
as it is sent or have sendmail fix it on the way out.

> > 
> > Most smtp receivers these days will not accept email if the
> > sender's domain is not DNS-resolvable.  Some sites will also
> > refuse it if the IP and DNS don't match, but that is less
> > common (and the RFC's explicitly permit that case - otherwise
> > multihomed hosts wouldn't work).
> 
> That's the problem - localhost.localdomain is not DNS-resolvable. 
> 
> The most confusing thing to me now is this: if I send a message as a
> normal user from the 'mail' command line, it gets delivered just fine;
> the From: line in the header reflects that the message is from
> 'localhost.localdomain', but the receiving mail server sees it as
> ultimately from my NAT'ing firewall (frwl.cullmail.com).
>
> However, if I send the message from the root account, it gets rejected
> by the destination host - the receiving host sees a From: header of
> 'localhost.localdomain'.
> 
> Why is this? Why is mail from root handled differently than mail from a
> regular user?

Your sendmail.mc probably has:
MASQUERADE_AS(`frwl.cullmail.com')
and
EXPOSED_USER(`root')
which says to change the From: header if it matches the local host
name, except for the root user.  If you have several machines with
root's mail forwarded to a common location you might want to know
where it came from.  Rebuild without the EXPOSED_USER if you don't
want that.

By the way, I don't see an MX or A record in DNS for frwl.cullmail.com.

-- 
  Les Mikesell
    lesmikesell at gmail.com