On Fri, 19 Mar 1999, Paul Walsh wrote:
> "If an attempt to look up the name of a host from its IP address
> fails because there is no PTR record in the DNS, Exim
> takes a hard line by default. "
>
> Which, to me means that any host whcih doesn't have a reverse DNS entry will
> get rejected by default.
No. That states what happens when it tries to look up a name. It doesn't
look up a name unless it needs the name. Name lookups can be expensive.
Busy ISP systems tend not to bother with them.
> Am I missing something, or is rejection of mail from IP addresses without
> names dependant on there being a sender_host_reject or
> sender_host_reject_recipients being present in the config file?
Sort of right. There are two cases:
(1) There is a host_reject of some sort which implies checking by name,
so a reverse lookup has to be done. If all your checks are by IP
address, no lookup is necessary, and of course none is necessary if you
aren't doing any host checking.
(2) helo_verify is set, so again it needs a name.
If you want to force rejection for unregistered IP addresses but
otherwise not reject anything, you can always set
sender_host_reject = some.random.junk
--
Philip Hazel University of Cambridge Computing Service,
ph10@??? Cambridge, England. Phone: +44 1223 334714.
--
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