On Fri, 3 Oct 1997, Wayne Folta wrote:
> >local_domains = ccmail.comstat.com:ctd.comsat.com:comsat.com
>
> This is like a discussion I had with Philip offline. Many of us believe,
> for whatever reason, that "netmail.to" is a domain, but
> "server1.netmail.to" is a host. Exim does not make this simplistic
> distinction.
Exim terminology follows that used in the RFCs. Unfortunately, the word
"domain" is very confusing (I was confused when I first met it in
connection with the Internet) and has been used by some people with the
meaning described above, which is NOT the meaning used in the RFCs.
Humpty Dumpty said "When I use a word, it means exactly what I want it
to mean, neither more nor less." but I don't think we'd get very far with
global communication if we all behaved like that. :-)
In RFC 1123 we find
Whenever a user inputs the identity of an Internet host, it SHOULD
be possible to enter either (1) a host domain name
^^^^^^^^^^^^^^^^
and later on:
The text of RFC-821 suggests that mail is to be delivered
to an individual user at a host. With the advent of the
domain system and of mail routing using mail-exchange (MX)
resource records, implementors should now think of
delivering mail to a user at a domain, which may or may
not be a particular host.
> A related area for misunderstanding is what it means to relay mail. My
> naive belief would be that mail passing through my server to another is
> relayed. But exim considers some locally-delivered mail to be relayed.
No. That is not true. Exim considers mail to be relayed if it comes in
from a remote host and has an address which is not one of the local
domains as defined by local_domains and related options.
I think you might be misunderstanding the word "local". In Exim it means
"delivered on the same machine". It does not mean "delivered to some
other machine at my site" - Exim can't tell the difference between a
machine on your site and a machine on the other side of the world. There
is just "this host" and "the rest".
> This causes a problem for the newbie. You look at eximstats and see what
> mail is being relayed. You think about users who will use your server as
> their SMTP server. You create some anti-relay settings to allow the good
> stuff through... And it rejects all kinds of locally-bound email.
If Exim is rejecting mail *for the local machine* (i.e. in its sense of
the word "local") then it is malfunctioning.
> Why? Because an exim process can relay within itself and it uses the
> anti-relay variables in the process. Unfortunately, there is no record made
> of such implicit relaying, you have to know what is going on.
Sorry, I don't understand what you are referring to here. However, Exim uses
the anti relay stuff only when accepting mail from another host.
Isn't English fun? We like to think we all speak the same language,
but...
--
Philip Hazel University Computing Service,
ph10@??? New Museums Site, Cambridge CB2 3QG,
P.Hazel@??? England. Phone: +44 1223 334714
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