Many thanks for the sanity check, Mr. Postfix
I am using the explicit domain name rather than $mydomain mainly on client
machines because they are not guaranteed to have the same domain as the mail
servers.
Is there any way to shorten/remove the delay I saw in the MX-failover ?
Again, many thanks for the quick response
From: <owner-postfix-us...@postfix.org> on behalf of Wietse Venema
<wie...@porcupine.org>
Reply-To: Postfix users <postfix-users@postfix.org>
Date: Wednesday, October 26, 2022 at 14:09
To: Postfix users <postfix-users@postfix.org>
Subject: [EXTERNAL] Re: MX records and relayhost: Am I going this correctly ?
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://gcc02.safelinks.protection.outlook.com/?url=https%3A%2F%2Faccess.redhat.com%2Fsolutions%2F4025391&data=05%7C01%7Cdaniel.e.white%40nasa.gov%7Cec472cf769824ce55a8e08dab77d47f4%7C7005d45845be48ae8140d43da96dd17b%7C0%7C0%7C638024045956278652%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=WFi3rKroF5DsLvomCS5NcG9%2ByCKQOlC3ITI1KFW4oyU%3D&reserved=0
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
