On Tue, Jan 28, 2025, Fehlauer, Norbert via mailop wrote: > if a domain has no mx record than a fallback to A/AAAA for the > domain is possible.
It's not just "possible", it's required to check. > Is this fallback only to happen when no mx record exists Yes. See RFC 5321. 5.1. Locating the Target Host If an empty list of MXs is returned, the address is treated as if it was associated with an implicit MX RR, with a preference of 0, pointing to that host. If MX records are present, but none of them are usable, or the implicit MX is unusable, this situation MUST be reported as an error. -- Please don't Cc: me, use only the list for replies. _______________________________________________ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
