> Ok, a curly one: our IMGate box is acting as the smarthost for our test
(and
> eventually production) IMail box. So far it works really well, and both
> internal (old-system bound) and external mail is going through. However,
we
> have a mail-to-pager system running, and I need the IMGate box to relay
mail
> to that system as appropriate. Trouble is, the system is hard-coded to use
> some fake domains rather than subdomains of our real one.
>
> In short, any mail to ourdomain.sms or ourdomain.pager from inside the
> company has to go to a specific host. Any mail to those domains from
outside
> the company must bounce. I already have entries in transport.map to take
> care of the mail routing, and they're not listed in relay_domains.map so
> outsiders can't relay mail there. Problem is that the
> reject_unknown_recipient_domain restriction is bouncing the mail for
> everyone since those domains don't exist.
>
> I know this can be fixed by setting up zones on our DNS server for .sms
and
> .pager, but I'd like to avoid that to minimise problems in case ICANN ever
> approve a real .sms or .pager TLD. I tried entries in the /etc/hosts file
> (which worked for Sendmail) but Postfix seems to ignore that.

Odd, the HOSTS file works fine for me.  I used it to fix a few faked things
here.

Move permit_mynetworks up is one option.

> I was going to add a line immediately above
reject_unknown_recipient_domain
> that says something like hash:/etc/postfix/pager_domains.map, and then
> create that file as follows:
> ourdomain.sms permit_mynetworks
> ourdomain.pager permit_mynetworks
>
> Before I do that on what is now a production system, is it going to do
what
> I want? That is, will it:
> - Allow mail to those fake domains from internal IP addresses,
> - Continue to deny mail to those fake domains from elsewhere,
> - Not affect any other mail.

Actually, I like your use of permit_mynetworks inside a map better.  It
should create the exemption you want, but not open up more holes.

This following the principal of "least window of opportunity for abuse" is a
very good one.

--Eric


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