Re: [exim] Exim always expands sender_rcvhost to unverified …

On 18/11/2021 19:10, Bill Cole via Exim-users wrote:
> Also welcome, short of a patch, would be clues about how to detect in an Exim-written Received header when a SMTP client IP has no rDNS or the rDNS name doesn't resolve to the client IP.

It would be more reliable to interpret an Authentication-Results header (cf. RFC 8601),
assuming the Exim config creates one using the intended expansion item

eg:

add_header = :at_start:${authresults {$primary_hostname}}


In either case you would be dependent on an rDNS check having
done; this is not automatic and can be avoided by the config.

Checks of the peer IP against a hostlist item which is a name
will cause one, as will matching the host_lookup option or
an explicit verify=reverse_host_lookup ACL condition.
--
Cheers,
Jeremy