Thanks for your help. I have two questions about special cases for
your suggested routers.
1. Suppose the mail is (correctly) addressed to some alias of some local
network machine. The internet router will attempt to send it to the
internet. If no DNS entry is found, the router fails and the message goes
to the local router. Can I be sure that the local alias will not **by
accident** match anything in DNS and thereby get sent to some very wrong
computer?
(Local network mail can have sensitive/proprietary information. My
company could get sued it this information was passed to the wrong hands.
If exim tried to send local mail locally *first*, I would feel much
happier.)
2. Suppose the mail is addressed to the internet. My internet connection
is dialup. Suppose that the address is valid but the DNS lookup in the
internet router fails by timeout or other benign, temporary, but common
problem. The message then goes to the local (network) router which tries to
connect to the internet domain directly. (Nothing restricts the local
router to local network domains, right?) The internet domain probably will
not want to accept mail from a dialup connection like mine. (That's why
ISPs provide a smarthost, right?) If I am lucky, the domain will refuse my
connection return an error, and the message will go safely back into the
queue. If I am unlucky, the domain could, I suppose, accept the mail but
drop the mail in /dev/null when it determines that my dialup ISP connection
is not a proper sender. This seems to put my mail at the mercy of foreign
hosts and their configured response to bad connections. Can I be confident
that internet mail sent by the local router will not be lost in this way?
(I was hoping that there was somekind of router that I could create,
possibly using one of the verify_only type options, that would do the
gethostbyname (/etc/hosts) lookup first so that the later routers could make
(relatively) fool-proof decisions. I wasn't able to figure out which
options would do this.)
I hope that the above made sense. I am just a beginner at this....
Many thanks,
John
On Mon, Sep 13, 1999 at 09:38:22AM +0100, Philip Hazel wrote:
>
> internet:
> driver = lookuphost
> transport = remote_smtp
>
> local:
> driver = lookuphost
> transport = remote_smtp
> gethostbyname
>
> The first one looks up the domain in the DNS - if it finds it, fine. If
> not, the second one looks up the domain by calling gethostbyname()
> which should consult /etc/hosts. Or you could use a domainlist router
>
> local:
> driver = domainlist
> transport = remote_smtp
> route_list = "* $domain byname"
>
