Dominic Raferd:
> I'm using Postfix 3.1.0. If a message is rejected by an onward server
> with a transient error message (e.g. 421-4.7.0 'temporarily rate
> limited') then my postfix immediately tries any other specified MXs per
> the recipient address and if these give the same response (as they tend
> to) it immediately sends using the specified smtp_fallback_relay.
>
> Is there a way to get it instead to try again, after a delay, to the
> primary onward server(s) (whether the one specified as relayhost or, if
> no relayhost is specified, the MXs per the recipient address), and only
> if these fail again (or after n times) then fallback?
Why not address the root cause: you are violating the receiver's
mail rate policy. You can use xxx_transport_rate_delay for a global
limit, xxx_destination_rate_delay for rate limit per destination,
or kernel-based traffic shaping.
Wietse
