valen at tuatha.org wrote:
> I have no idea. I've changed a few (like use_domain etc). But it doesn't
> seem to matter. I think that broken mailers expect to be able to do a
> hostname lookup on the machine that sent the thing. Seeing as my machine
> gets it's IP address via DHCP, that's not going to happen...
Sendmail can be configured to check that the sender domain is valid.
Note that there doesn't have to be an A record for the domain, an
MX will do. I guess the reasoning is that mail with a sender that
can't be sent to doesn't deserve to be delivered. And I agree...
However, because a domain lookup failure is a retryable error,
sendmail doesn't bounce the message permanently. Instead it returns
a 'try again later' error code, hoping that the relevant DNS records
will have appeared by then.
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