Explicit priority MX with only AAAA record

[SM]

At 06:32 25-06-2008, Marcus Stoegbauer wrote:
>We had this setup for about 1.5 years for our (really small) company 
>domain and I didn't receive any complaints during this time that 
>mails couldn't be delivered or got lost.
>However there are said to be mail daemons which don't behave well 
>when the first MX can't be resolved to an A record and stop 
>delivering the mail altogether.

It's not a mail daemon problem as such.  You'll run afoul of antispam 
filters with such a setup.  There is a well-known email service 
provider who will not accept messages from domains setup like that.

>I don't see the upside on changing from "AAAA/A" to "first AAAA, 
>then A". In my eyes your current setup is the best and easiest 
>solution because it should give you exactly the same behaviour, no 
>matter which IP protocol you're using.

It's a good test for brokenness.  Don't do it unless you can afford 
the problems that come with it.

Regards,
-sm