Yes thats the only reason I could think of, but unfortunately this is not the case. The sender tried to deliver a normal mail from his mta. I would guess that his firewall or DNS wasn’t working correctly, like Stuart said.
Regards Norbert Von meinem iPhone gesendet Am 28.01.2025 um 19:50 schrieb Alessandro Vesely via mailop <[email protected]>: On Tue 28/Jan/2025 18:49:01 +0100 Fehlauer, Norbert wrote: Hi, Thanks. So, if a domain has correct defined mx records only those can be used and if they are not reachable for any reason there should never be an attempt to reach the implicit MX RR of the domain. Correct. The reason I'm asking is I got NDRs from external senders (a few days apart from each other) which tried to deliver mails to our domain A record, which is not possible. Anyone has an idea what could cause external senders try to send to the implicit mx instead of our mx? The same senders do not had problems before or after this single event (at least not to my knowledge). Hm.. if someone tried to send a message using MAIL FROM:<[email protected]> then bounces would be directed to 85.13.128.116, since that host has no MX. Best Ale -- _______________________________________________ mailop mailing list [email protected] https://list.mailop.org/listinfo/mailop
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