Hello, I set up a mail server zone to have an IPv6-only primary and a dual-protocol secondary, like this:
; SMTP chooses lower-priority first, so smtp-primary is preferred example.com. 300 MX 10 smtp-primary.example.com. example.com. 300 MX 100 smtp-secondary.example.com. ; smtp-primary is IPv6-only smtp-primary.example.com. 300 AAAA 2001:DB8::1 ; smtp-secondary has both IPv6 and IPv4 addresses smtp-secondary.example.com. 300 AAAA 2001:DB8::2 smtp-secondary.example.com. 300 A 192.0.2.11 Mail delivery via IPv6 works fine (as you would expect), and mail delivery from some IPv4-only servers also works fine (as I think the standards dictate). My concern is that some mail servers may choke on this setup. For example, http://mailtester.com complains "Network is unreachable". Of course, I also worry about all the spammers who may not be able to deliver because of incomplete mail implementations on the trojans and other viruses infecting their zombie hosts. 😉 Does anyone have any experience with a similar setup? Have there been problems? Cheers, -- Shane
