On 2 Sep 2021, at 23:24, Jeremy Harris via Exim-users <[email protected]> wrote: > On 02/09/2021 20:25, krzf83--- via Exim-users wrote: >> # nc mx.poczta.onet.pl 25 >> 220-mx.poczta.onet.pl ESMTP >> 521 5.7.1 Service unavailable; client [144.76.50.172] blocked using >> postscreenbl.opbl.onet.pl.local > > That is not a consistent response. The first line is a 220 (with a flag > saying it will be a multi-line response). The second is a 521 (without > the flag, hence the last line). > > All the lines of the response should have the same code > (RFC 5321 section 4.2.1 last para: > "In a multiline reply, the reply code on each of the lines MUST be the > same." > )
This is postscreen, see: http://www.postfix.org/POSTSCREEN_README.html The site can configure it correctly to delay the enforcement until a mail transaction, but have instead gone with “drop”. Because the DNSBL check is run in parallel with pre-greeting tests, you get the “teaser” 220- followed by the 521 failure. It’s obviously wrong, but perhaps Exim should consider the last line of a response instead of the first for purposes of evaluation? Cheers, Sabahattin -- ## List details at https://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/
