White, Daniel E. (GSFC-770.0)[AEGIS]:
> MX Records:
>
> mydomain.tld. 33 IN MX 10 relay-1.mydomain.tld.
> mydomain.tld. 33 IN MX 20 relay-2.mydomain.tld.
>
> with relay-1 and relay-2 having appropriate A and PTR records.
>
> Then in /etc/postfix/main.cf, I have
>
> relayhost = mydomain.tld
>
> I have seen this work with relay-1 unavailable.
This is the obvious (to me) approach when the domain has multiple
MX hosts. It is also similar to the first relayhost example in the
stock main.cf file:
relayhost = $mydomain
> The outgoing message sat in the queue for a brief time, then went
> out through relay-2.
>
> I found a Red Hat solution https://access.redhat.com/solutions/4025391
> that suggests using
>
> relayhost = [relay-1.mydomain.tld]
> smtp_fallback_relay = [relay-2.mydomain.tld]
This also works, but it would be less obvious to me.
Wietse
