Am 09.08.2016 um 18:08 schrieb Kevin Golding:
Based on what you're trying to do:
man dig
don't help, see below
or depending on your resolver possibly:
man drill
don't help, see below
Whilst I agree it is slightly more effort to set-up whitelisting by
looking up the details first it would still be far more resource
efficient on your servers
that don't catch the problem if the MX changes that you need to
permanently watch your "whitelist_from_rcvd" and maintain them
his point is pretty sure that he want to be able to rely on the senders
DNS like whitelisting by DKIM or SPF does
given the amount of DNS records in summary (RBL, URIBL, DKIM, SPF) that
single one is not a topic for "more resource efficient" and in any case
outweights the maintainance burden of "whitelist_from_rcvd" lines
