Thank you again. Great information. ______________________________________________________________________________________________
Daniel E. White daniel.e.wh...@nasa.gov<mailto:daniel.e.wh...@nasa.gov> NASCOM Linux Engineer NASA Goddard Space Flight Center Office: (301) 286-6919 Mobile: (240) 513-5290 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 15:38 To: Postfix users <postfix-users@postfix.org> Subject: Re: [EXTERNAL] Re: MX records and relayhost: Am I going this correctly ? White, Daniel E. (GSFC-770.0)[AEGIS]: 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 ? By reducing smtp_connect_timeout from the default 300s to a more reasonable value, maybe 10-30s. Note that Postfix will shuffle the order of equal-preference MX hosts, so that a down server will delay only some of the traffic. Wietse Again, many thanks for the quick response From: <owner-postfix-us...@postfix.org<mailto:owner-postfix-us...@postfix.org>> on behalf of Wietse Venema <wie...@porcupine.org<mailto:wie...@porcupine.org>> Reply-To: Postfix users <postfix-users@postfix.org<mailto:postfix-users@postfix.org>> Date: Wednesday, October 26, 2022 at 14:09 To: Postfix users <postfix-users@postfix.org<mailto: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%7C157b6b61ac174ded95ec08dab789b6c5%7C7005d45845be48ae8140d43da96dd17b%7C0%7C0%7C638024099350096166%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=W%2BFFkuCrI0261JyqNAgyuuzngImMdHnVMl3HYmlRKQs%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
