fdnsmxalist - resolve a list of MX records and their corresponding A
records for hostname
fdnsmxalist [-x] <hostname>
fdnsmxalist will attempt to look up a list of MX records for hostname.
If any are found, they are printed to standard output seperated by
newlines in the format:
Protocol (Priority) hostname:port
The program then looks up lists of A and AAAA records for each MX
record, and prints them to standard output, one IP per line. Lines are
printed to standard output starting with "ERROR: " if any MX records
have no corresponding A or AAAA records, are CNAMEs (an RFC violation),
or have A or AAAA records which point to non-routable IP addresses.
If the -x switch is passed on the command line, the program outputs
machine-parsable XML instead of the human-readable tree.
Exit codes for the program are:
0 - Everything looks fine
1 - An MX has a non-routable IP
2 - An MX doesn’t exist
3 - An MX is a CNAME
4 - An MX is an IP address
100 - Invalid syntax
103 - DNS timeout or host does not have MX records
Ian Gulliver <firstname.lastname@example.org>