It appears that Fehlauer, Norbert via mailop <n.fehla...@systema-online.de> said: > >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.
That is correct, although since this is the Internet, you can't assume that the people who wrote random mail software actually read the specs they purport to implement, or debugged it properly. >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? See above. Their systems are broken, don't worry about it. Maybe their code got some sort of soft error on the MX lookup and misinterpreted it as a NOERROR or NXDOMAIN. R's, John PS: >Please don't Cc: me, use only the list for replies. Please send me a copy of any replies since they get sorted differently. _______________________________________________ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
