Is it possible to get access db *blocking* based on PTR only? [without DIY]

I understand why sendmail can not use PTR without "closing A record" to
*grant privileges* but I see no special reason why it can be used for
*revoking privileges* :-)

--
[pl2en: Andrew] Andrzej Adam Filip : anfi@priv.onet.pl : anfi@xl.wp.pl

In article <87bqnnqk5i.fsf@anfi.homeunix.net> Andrzej Adam Filip
<anfi@onet.eu> writes:
>Is it possible to get access db *blocking* based on PTR only? [without DIY]
>
>I understand why sendmail can not use PTR without "closing A record" to
>*grant privileges* but I see no special reason why it can be used for
>*revoking privileges* :-)

Maybe with this:

use_client_ptr If this feature is enabled then check_relay will override
its first argument with $&{client_ptr}. This is useful for
rejections based on the unverified hostname of client,
which turns on the same behavior as in earlier sendmail
versions when delay_checks was not in use. See doc/op/op.*
about check_relay, {client_name}, and {client_ptr}.

Doesn't seem to apply only to blocking though, so I guess that part
would have to be DIY - i.e. never use Connect:name.dom for granting
anything. Or trust that the spammers aren't clueful/resourceful enough
to fake the PTR record based on who they're sending to.

--Per Hedeland
per@hedeland.org