On Thu, Jun 26, 2025 at 10:33:14AM +0200, Support 3Hound via mailop wrote: > Dear list, > is it fair/correct to check the existence of a mailbox for about 30/50 mail > addresses/day? > They quite always will be present unless misspelled or typo that may be a > couple in a month. > We must RSET and then QUIT every the smtp connection just after the RCPT TO > answer because we must check the data but we cannot contact these users.
On first contact, that would receive a "451 Temporary failure, please try again later." here, courtesy of https://man.openbsd.org/spamd. What happens after that, depends on what you tried to verify. * if you retry delivery to an address that is already in our list of spamtraps[1], the source address for the connection will be added to the hourly-exported blocklist. * if you retry delivery to an address that is valid here or not already a spamtrap, the next attempt will be allowed on to the content filtering and potentially delivery that our actual MTA performs. * if the address you are trying to check is not a valid one here but not yet a spamtrap, it likely will become one the next time I get around to running those find-and-add-spamtraps scripts You might also enjoy reading some of my field notes such as https://nxdomain.no/~peter/twenty-plus_years_on_smtp_callbacks_are_still_pointless.html https://nxdomain.no/~peter/a_life_lesson_in_mishandling_smtp_sender_verification.html https://nxdomain.no/~peter/badness_enumerated_by_robots.html and links therein. So yes, you might say the practice is somewhat frowned upon. [1] https://nxdomain.no/~peter/traplist.shtml, supplemented by https://nxdomain.no/~peter/traplist_ethics.shtml -- Peter N. M. Hansteen, member of the first RFC 1149 implementation team https://bsdly.blogspot.com/ https://www.bsdly.net/ https://www.nuug.no/ "Remember to set the evil bit on all malicious network traffic" delilah spamd[29949]: 85.152.224.147: disconnected after 42673 seconds. _______________________________________________ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
