My test with postfix yielded: Status: 5.4.4 Diagnostic-Code: X-Postfix; Name service error for name=abx.ca type=MX: Malformed or unexpected name server reply
so at least it hard failed. - mark On 2016-02-28 12:07 AM, John Levine wrote: >> What is an MTA supposed to do with a message addressed to a domain with >> a NULL MX? > > Reject it with a 556 status code and 5.1.10 enhanced status code. If > the message was already relayed, return a DSN if it makes sense. See > section 4.1. > > You can also feel free to reject mail if the return address has a null > MX since you can't reply; in that case it's status 550 and 5.7.27. > >> I'm looking at some logs and seeing attempts to deliver email to lots of >> domains with NULL MX enabled (that have been so for years) and wondering >> if I can safely mine these logs and add all the originating MTA IPs to >> an internal RBL. > > That seems reasonable. Any MTA that tries the A address if you > publish a null MX (that's "domain MX 0 .") is so broken that it > deserves to die if it's not already spamware. There are plenty of > MTAs that will sit on the message for a week hoping the next time they > look up the MX it will be different, but I can't recall seeing any > legitimate MTA for a long time that falls back to A if it finds an MX. > > The RFC is new but the draft was kicking around since 2006, and was > never controversial. > > R's, > John > -- Mark Jeftovic, Founder & CEO, easyDNS Technologies Inc. Company Website: http://easydns.com Read my blog: http://markable.com +1-416-535-8672 ext 225 _______________________________________________ mailop mailing list mailop@mailop.org https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop
