Hai, First sorry to have the ips and name anonymized, i had to do that. I cant expose details until i first talked to the company in question. Thas a moral thing to do in my believe. And i need to be sure that i tell the right info when i do that.
The "helo=<name >" space was a copy past error, sorry missed that one. Main reason is posted, and sorry about my english, its not my native langauge. I needed to understand this situation bit more. What by rfc is allowed. After reading the rfc, in english, wasnt clear enough. I digged a bit more and i found that . I found https://tools.ietf.org/html/rfc5321#section-2.3.5 Only resolvable, fully-qualified domain names (FQDNs) are permitted when domain names are used in SMTP. In other words, names that can be resolved to MX RRs or address (i.e., A or AAAA.. so and im not asking to help solve this but im asking is my interpetation of the rfc correct. The problem server setup is as followed. 2 servers its ptr records refer to the helo hostname the same name (mx1.domain.tld) The helo hostname (mx1) has no A record but the helo is defined as mx record. As are mx2.domain.tld and mx3.domain.tld both have an A record and PTR record Now my server is rejecting any incorrect helo hostnames. Because the rfc stats: "names that can be resolved to MX RRs or address (i.e., A or AAAA.." And due to legal resons i must correcly identify the sending server. I do enforce most rfc parts, but i dont reject in incorrect client hostnames due to for example missing ptr records and my customers dont have to make much trouble to make that work, a simple A record in the dns is sufficient. A few big providers here dropped there relay which made a mess in mailing, lots of mis configuration, so i dont reject incorrect client hostnames and for customers ist much harder to set the ptr record, that take to much time at most providers. After adding the a record it mostly works again within an hour. I believe this client is rejected due to missing A record on the MX record. A change of the helo hostname to the client hostnames solves it and make them full rfc compiant in my opionion. So question is, is the rfc interpetation correct this way? And be nice, im asking this because im always helping our customers to make more rfc compliant setups because it simply make everyone happy. Now that you ended here.. , thank your for reading it all. :-) And Viktor, if a next help is needed, i'll post the complete log ok. Best regard, Louis > -----Oorspronkelijk bericht----- > Van: njo...@megan.vbhcs.org [mailto:owner-postfix-us...@postfix.org] > Namens Noel Jones > Verzonden: donderdag 15 december 2016 18:40 > Aan: postfix-users@postfix.org > Onderwerp: Re: DNS round robin on helo? > > On 12/15/2016 10:01 AM, L.P.H. van Belle wrote: > ... > > I looks to me and incorrect implementation, what do you guys think. > ... > > All this is allowed, legal, and unsurprising. > > Not everything that is allowed is wise. Ideally, each host (or each > connection on a multi-homed host) should have its own unique > hostname/A/PTR/HELO for mail, with higher lever MX records listing > all of them. If this is not your server, there is nothing to > complain about. > > If their HELO name really has a trailing space, that would be a > config error. But config errors on HELO names are not unusual. > > > > -- Noel Jones
