Any filtering is an evil and there is not any standard on how to implement spam filtering. Any spam filter has false positives, and Earthlink probably accepts false positives from this rule because it's effective.
DKIM and DMARC require message DATA to be sent, especially corporate / smaller ISPs admins do not have domain reputation data and prefer spam messages to be rejected before DATA, so validating PTRs and HELO/EHLO is quite common and is not specific to Earthlink. DKIM/DMARC authenticate mesage content's author and doesn't put any guarantee on message content. You can send DKIM-signed spam message to millions of recipients via botnet and it passes DKIM/DMARC checks, but it fails PTR checks in most cases. There are a lot of technical things affecting deliverability. With different mail system you can have different issues because oif this. Some time ago I've compiled a checklist you can find useful: https://team.mail.ru/technical-recommendations-for-email-senders/ 14.12.2017 17:27, Ryan Prihoda пишет: > > > What about SPF, DMARC, DKIM ? I am sending 250k/day and only Earthlink > seems to care. How many checks are actually necessary ? > > -Ryan > > On 12/13/2017 03:32 PM, Vladimir Dubrovin via mailop wrote: >> >> >> Not only Earthlink cares, it's a standard procedure. >> This validation confirms your IP really belongs to the domain. >> This is standard validation for PTR everyone does, without this >> validation you can set PTR to arbitrary domain (e.g. example.com). >> Not everyone rejects messages based on this check, but it's also an >> option, see e.g. >> http://www.postfix.org/postconf.5.html#reject_unknown_client_hostname >> >> >> 14.12.2017 0:02, Ryan Prihoda пишет: >>> >>> William, >>> >>> Yes our PTR is set correctly, but our domain does resolve to a >>> different IP. Why does only Earthlink care about that ? Seems silly. >>> >>> Sincerely, >>> >>> *Ryan Prihod**a >>> *Systems Administrator >>> >>> >>> *dyna**Connections****Corp. >>> *1101 S. Capital of TX Hwy. >>> Bldg. H, Suite 130 >>> Austin, Texas 78746 >>> rprih...@dynaconnections.com <mailto:rprih...@dynaconnections.com> >>> www.dynaconnections.com <http://www.dynaconnections.com/> >>> >>> >>> On 12/13/2017 02:47 PM, W Kern wrote: >>>> >>>> its misleading. >>>> >>>> We saw that a few weeks ago. >>>> >>>> Make sure the FQDN you reverse zone file provides, also resolves >>>> back to the same IP. >>>> >>>> We were just as confused. The PTR was there, but because of a typo >>>> it didn't resolve. >>>> >>>> Fixed that and Earthlink was happy. >>>> >>>> Sincerely, >>>> >>>> William Kern >>>> >>>> Pixelgate Networks. >>>> >>>> >>>> On 12/13/2017 12:21 PM, Ryan Prihoda wrote: >>>>> >>>>> Hello all, >>>>> >>>>> We are getting errors from one of our servers. >>>>> >>>>> 550 ERROR: No or mismatched reverse DNS (PTR) entries >>>>> >>>>> When, in fact there is only one record for that IP. Can anyone >>>>> from Earthlink look into this for us ? >>>>> >>>>> Sincerely, >>>>> >>>>> *Ryan Prihod**a >>>>> *Systems Administrator >>>>> >>>>> >>>>> *dyna**Connections****Corp. >>>>> *1101 S. Capital of TX Hwy. >>>>> Bldg. H, Suite 130 >>>>> Austin, Texas 78746 >>>>> rprih...@dynaconnections.com <mailto:rprih...@dynaconnections.com> >>>>> www.dynaconnections.com <http://www.dynaconnections.com/> >>>>> >>>>> >>>>> >>>>> _______________________________________________ >>>>> mailop mailing list >>>>> mailop@mailop.org >>>>> https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop >>>> >>>> >>>> >>>> _______________________________________________ >>>> mailop mailing list >>>> mailop@mailop.org >>>> https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop >>> >>> >>> >>> _______________________________________________ >>> mailop mailing list >>> mailop@mailop.org >>> https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop >> >> >> -- >> Vladimir Dubrovin >> @Mail.Ru >> >> >> _______________________________________________ >> mailop mailing list >> mailop@mailop.org >> https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop > > > > _______________________________________________ > mailop mailing list > mailop@mailop.org > https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop -- Vladimir Dubrovin @Mail.Ru
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