testmxlookup domain
testmxlookup
is a diagnostic utility that lists the names and
IP addresses of mail relays that receive mail for the given domain.
testmxlookup
sends a DNS MX query for the specified domain,
followed by A/AAAA queries, if needed. testmxlookup
lists the
hostname and the IP address of every mail relay, and its MX priority.
The error message "Hard error" indicates that the domain does not exist, or does not have any mail relays. The error message "Soft error" indicates a temporary error condition (usually a network failure of some sorts, or the local DNS server is down).