On 13.03.17 17:49, Andy Smith wrote:
I can see that the domain in question does have A and MX records, possibly issues are that the A record doesn't match the PTR for the IP returned by the A record and that one of the MX records doesn't have a PTR. I'd be keen to know if one or both of these are the issue, and what the situation WRT RFCs on email DNS says about what are required for proper operation of email.
This has never been an issue, and you should never expect that to match. There's no point in checking those. Please, do not advise enyone ever to check for this combination (1). What is supposed to match: sending IP => PTR => A/AAAA => sending IP MX => A/AAAA => IP (public aka no private ranges) See? no reverse checks in the latter case. You would be surprised that companies like google, aol, yahoo (at the time I last checked, and I did this multiple times, see (1)) don't have rDNS for those - that's because there's no requirement (and no sane reason) for that.
I've already had to ask the owners of the domain to correct an issue where their sending server's A record didn't match the PTR and was triggering the RDNS_NONE rule (as detected by Exim), so if I'm going to convince them to do more modifications I'd prefer to know what I was talking about,
The sending IP is NOT the MX record - those are two separate things. Yes, it may be the same server, but the PTR is checked on incoming mail, and _never_ on the MX->A record. Simply - don't mix those, you'll lose focus on the real issue. (1) In the past I got customer complaints about them being rejected because "their MX records pointing to A's that didn't matchtheir PTRs". This never turned out to be true - they were blacklisted, they were refused because their HELO string was nonexistent, or they just made complaint without any real problem. Once the admin wasn't even able to translate clear error message from english, nor search for the error message on the net... Simply, don't do that. -- Matus UHLAR - fantomas, uh...@fantomas.sk ; http://www.fantomas.sk/ Warning: I wish NOT to receive e-mail advertising to this address. Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu. Windows 2000: 640 MB ought to be enough for anybody
