On 3/1/15 2:47 PM, John Levine wrote:
(1) example.com. MX 23 primary.example.com. example.com. MX 42 backup.example.com. backup.example.com. A/AAAA <address of server a> backup.example.com. A/AAAA <address of server b>Here I presume you meant to have two A records for primary.example.com. A name with several A records is supposed to mean that there's one host with interfaces on several networks. If a client tried to contact one of the addresses and it failed, it'd be reasonable to go to the backup without trying the other A records.(2) example.com. MX 23 primary-a.example.com. example.com. MX 23 primary-b.example.com. example.com. MX 42 backup.example.com.This says what I think you mean. By the way, why do you have a backup MX? These days, it's hard to keep the spam filtering on the backup in sync with the primaries, and anyone who's not a spammer will wait and retry for long enough that you're going to get all of the real mail. Backup MXes made sense in the 1980s when networks were flaky and there were a lot of servers on intermittent dialup connections. They don't make much sense now.
I agree with John on all points. If you have three servers, give them 3 MX records of equal priority, and make sure that they are all given equal care and attention.
hope this helps, Doug _______________________________________________ mailop mailing list [email protected] http://chilli.nosignal.org/mailman/listinfo/mailop
