If you are load balancing, why are you advertising two different IPs? I think what Jim Kennedy has honed-in on is correct, and that the issue is likely HELO/EHLO checking if your PTR records check out.
https://en.wikipedia.org/wiki/Anti-spam_techniques#Strict_enforcement_of_RFC_standards (HELO/EHLO checking – RFC 5321) -- Espi On Thu, Feb 8, 2018 at 5:45 AM, Mayo, Bill <[email protected]> wrote: > I told Earthlink that we had 2 different IP’s for the mail server, and > that we had seen rejections from both. He asked for the first IP, which I > gave him. He then went to mxtoolbox.com and looked up the domain name. It > returned a different IP than the one I gave him and he suggested that was > an issue. I told him that was the other IP and that they were > load-balanced; that at any given time an A record lookup would return one > or the other. That said, the reverse DNS (PTR) record for each of the IP’s > is correct. He told me that he didn’t know what load balancing meant and > that he would have to talk to someone else to see what could be done. > > > > I am happy to admit I might have some misunderstandings about DNS, but I > don’t think that having multiple A records for a given domain name is > unusual. I therefore assume they wouldn’t actually try to confirm > legitimacy by doing an A lookup and comparing that to the IP. I do want to > be clear that he didn’t explicitly say that was the problem. I did try to > point out that their error message complained about a missing or mismatched > PTR record, and I believe that is all correct. > > > > *From:* [email protected] [mailto:listsadmin@lists. > myitforum.com] *On Behalf Of *Michael B. Smith > *Sent:* Wednesday, February 07, 2018 7:08 PM > *To:* [email protected] > *Subject:* [Exchange] RE: Earthlink Contact? > > > > I’m sorry, I can’t follow your logic. It seems to fall apart in the > sentence beginning “What EarthLink seems…” Could you be a bit more concrete > please? > > > > In general, I agree with Micheal – you shouldn’t have a PTR mismatch, but > that’s not what I get out of your explanation. > > > > *From:* [email protected] [mailto:listsadmin@lists. > myitforum.com <[email protected]>] *On Behalf Of *Mayo, Bill > *Sent:* Wednesday, February 7, 2018 4:46 PM > *To:* [email protected] > *Subject:* [Exchange] RE: Earthlink Contact? > > > > My attempts at [email protected] and [email protected] did not > work, so I tried the Twitter route. It took a while, but I did ultimately > get a response today where they gave me a phone number to call. So, thanks > to Michael and everyone else that responded. That said, based on the > conversation that I had, I would appreciate a reality check. > > > > We have 2 different ISPs and load balance outbound SMTP connections, as > well as inbound DNS queries. So, we basically have 2 different IP’s that > are used at the edge. We have an MX record that points to the domain name. > DNS lookups to that domain name will return one of the 2 IP’s. Both of > those IP’s will reverse lookup to the domain name. The HELO/EHLO greeting > from the server gives the same domain name as the MX record. Additionally, > we have an SPF record that indicates both of those IP’s. What Earthlink > seems to be initially suggesting is that they are doing an A record lookup > of the domain name and comparing that to the connecting IP address (which > seems contrary to the error message). In our setup, this will not always be > a match. I can understand that they would do a reverse DNS on the IP to > make sure it matches the HELO/EHLO greeting, and I can understand that they > might also do an SPF and/or MX lookup to make sure that matches. I don’t > understand doing a forward lookup and comparing that to the IP, since I > don’t think that having multiple A records for a given domain name is > particularly uncommon. Is what they are suggesting a legitimate issue? > > > > Bill Mayo > > > > *From:* [email protected] [mailto:listsadmin@lists. > myitforum.com <[email protected]>] *On Behalf Of *Michael B. > Smith > *Sent:* Friday, February 02, 2018 10:49 AM > *To:* [email protected] > *Subject:* [Exchange] RE: Earthlink Contact? > > > > Twitter shame them. @Earthlink and @weCareEarthlink > > > > And yes, I’m completely serious. > > > > *From:* [email protected] [mailto:listsadmin@lists. > myitforum.com <[email protected]>] *On Behalf Of *Mayo, Bill > *Sent:* Friday, February 2, 2018 10:16 AM > *To:* [email protected] > *Subject:* [Exchange] Earthlink Contact? > > > > We are having emails sent to Earthlink being intermittently rejected with > the reason “550 ERROR: No or mismatched reverse DNS (PTR) entries”. We have > done quite a bit of troubleshooting on this, and the problem does not > appear to be on our end. I actually have logs that show 2 consecutive > messages where the first one is accepted and the second one rejected. I > also see “421 Load too high” messages in the log from Earthlink when these > happen. > > > I am trying to figure out how to contact Earthlink to get some assistance, > but am striking out with how to contact them. The have a special page if > you are getting a “blocked by EarthLink” response, but that doesn’t apply > here. There contact page has chat support that requires you to provide an > Earthlink account. Does anybody know how to get in touch with someone at > Earthlink that could actually help with this problem? > > > > Bill Mayo >
