Postfix Fallback Relay Configuration

Discussion in 'HOWTO-Related Questions' started by aadeusi, May 16, 2008.

  1. aadeusi

    aadeusi New Member

    could someone please give me step-by-step instructions on how to configure the fallback_relay option in Postfix?
    I'm trying to set up a backup/secondary relayhost.
    The instructions are somewhat confusing to me and I was hoping for some assistance.

    Please see the details below:

    fallback_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, host:port, [host]:port, [address] or [address]:port; 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 specify "relay_transport = relay",
    • In 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.


    Any advice would be greatly appreciated.

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