Am 22.09.2017 um 18:19 schrieb Davide Marchi: > On Debian Jessie, Postfix 2.11.3 and Spamassassin 3.4.0-6, I've just > setup an MX email backup server and now I realize that new spam come > from the MX backup server.. > Is there any way to tell to reject any mail coming to the MX backup > server, if the primary server is up?
The easiest way by far is to shut down the backup server forever. Every sane MX host normally queues outgoing mail for five days and retries its delivery frequently, so when the primary MX is down for a short period of time, you'll loose nothing, because when he's up again all waiting mail starts to come in anyway. So the use case and need for a backup MX normally is quite narrow down to non existant for most people.
