On Mon, 5 Nov 2007, Phil (Medway Hosting) wrote: | I return a 450 for all mail with no rDNS. That then allows time for DNS to | recover if there were a delay or fault.
The 4xx response seemed to be the advice in the past, in the hope that a temporary DNS problem gets fixed. The downside is any legit sender with no rDNS at all (broken or otherwise) has to wait days while their message festers on their outbound queue, before they get informed you're not accepting it. Note that exim (since version 4.50) also has host_lookup_deferred, to make it easier to distinguish a DNS tempfail (where you issue 4xx) from a DNS hardfail (where you might well want to issue 5xx). See Michael H's post for example usage of this. -- ## List details at http://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/
