Rainer Dorsch wrote: > Am Montag, 18. Mai 2020, 19:58:06 CEST schrieb Dan Ritter: > > I think you're overcomplicating it. > > > > Your domain can and should have two or more MX records, with > > different priority levels. The MX records don't even have to > > point to names in your domain. > > > > Since you're using Let's Encrypt, certificates are free. So, > > for each mail server, set up an A and/or AAAA record. Add those > > to the MX records for your domain. Have LE produce certificates > > for the mail servers under the names they have assigned. > > > > Any mail sender will try each of your MX records, stopping when > > it gets to a working entry. Some spammers will try in reverse > > order, hoping that you don't have anti-spam measures on your > > secondary mail server. > > Thanks, Dan, for your quick reply. I was not concerned about incoming mail to > my domain using the MX record. > > I was more concerned about the outgoing server configured in the email > clients > and used to send main from my domain (at least so far I did not understand > that they can make use of the MX record).
It depends on the MTA you choose for your email clients, but unless you choose the very simplest systems, they can be configured to look up the MX record and use that. (Postfix has a fallback_relay option, Exim can accept multiple hosts in a route_list statement, and so forth.) Finally, you could set up each of your mail servers to call themselves smtp.domain, and use any number of failover mechanisms to get a single IP to whichever one is live. In practice, you probably should not bother with that. -dsr-
