4 ms·
If an MX record isn't present you can fall back on the A-record. (If, and only if, no MX record for the domain is present, treat the domain as if it had an MX
by stevekemp 6y ago
If an MX record isn't present you can fall back on the A-record.
(If, and only if, no MX record for the domain is present, treat the domain as if it had an MX record with the given domain as the target hostname and a preference value of 0)
- Arnt 6y agoIf you want to be pedantic... not in the relevant case, no. In the relevant case (the domain is syntactically invalid but the naïve check didn't discover that) the response without MX RRs already tells you that there won't be an A (or AAAA).