On Fri, Jun 16, 2023 at 12:41 PM John Possidente via mailop <mailop@mailop.org> wrote: > > A sender of legally mandated bulk mail who are very conscious of making sure > they're dotting every i and crossing every t (because they're required to) > asked me today whether port 25 pingback is still necessary. I immediately > thought, "Of course not," but on second thought (before speaking, yay) > realized that maybe I'm wrong. > > Does anyplace still reject mail from sources that don't answer on port 25?
No place that matters. Most ESPs have separate infra for outbound SMTP and inbound reply handling, and it's not the same servers, not the same IPs. Thus, the servers connecting outbound to deliver mail do not answer on port 25. This is how it was where I used to work and it was no impediment to billions of messages delivered monthly. And I never saw an instance where delivery was held up by waiting to see if the inbound infra could be reached on port 25 separately. Cheers, Al Iverson -- Al Iverson / Deliverability blogging at www.spamresource.com Subscribe to the weekly newsletter at wombatmail.com/sr.cgi DNS Tools at xnnd.com / (312) 725-0130 / Chicago (Central Time) _______________________________________________ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
