Help!!! Is there anyway Postfix can be configured to relay to a second/backup host in the event where the primary host is unavailable or down? I know that the 'relayhost' parameter only allows for single host relay, but I'm hoping there's a tweak or configuration change that can skirt that limitation. The use of external services e.g. BIND (DNS) and/or MX records is not an option in this case and neither is the use of a load-balancer. Therefore the configuration required has to be a function of Postfix itself. Please let me know if you have any thoughts or ideas that may help. Thank you.
Hi Falko. Thanks for the response. What I actually was looking for was this: allback_relay (default: empty) Optional list of relay hosts for SMTP destinations that can't be found or that are unreachable. With Postfix 2.3 this parameter is renamed to smtp_fallback_relay. By default, mail is returned to the sender when a destination is not found, and delivery is deferred when a destination is unreachable. The fallback relays must be SMTP destinations. Specify a domain, host, hostort, [host]ort, [address] or [address]ort; the form [host] turns off MX lookups. If you specify multiple SMTP destinations, Postfix will try them in the specified order. Note: before Postfix 2.2, do not use the fallback_relay feature when relaying mail for a backup or primary MX domain. Mail would loop between the Postfix MX host and the fallback_relay host when the final destination is unavailable. * In main.cf specify "relay_transport = relay", * In master.cf specify "-o fallback_relay =" (i.e., empty) at the end of the relay entry. * In transport maps, specify "relay:nexthop..." as the right-hand side for backup or primary MX domain entries. Postfix version 2.2 and later will not use the fallback_relay feature for destinations that it is MX host for. However, thanks again!!!!
