. > > Is there a sensible way to configure postfix to allow these messages > > with null sender addresses to be relayed without opening the smart > > host up to exploitation? > > Sending bounces is not "exploitation", but the "smart host" (really > submission service) policy is up to the ISP. Ask them.
I wasn't trying to suggest that sending bounces would be exploitation, rather that allowing *all* messages with a NULL sender to relayed through could potentially be exploited to send spam as <> > NO. Bounces MUST be sent with a null sender address. Otherwise, bounces > would elicit bounces in return creating mail loops, sometimes exponentially > growing, if a message elicits multiple non-delivery reports. Yes I know that and have referred to that point below. > The solution is to use a relay that permits bounces. Either the ISP relaxes > their policies, or a different relay must be found. As I feared, thank you for confirming. > > And before anyone comments, yes I know this isn't best practice as > > NDR's should have null sender addresses to stop loops (bouncing > > bounce-backs!). > > Not "should", MUST. Not "isn't best practice", rather prohibited. > > -- > Viktor. I understand and agree however in my experience you sometimes have to fudge things so they operate with incorrectly configured systems (against my own wishes!) James
