[plug] Postfix relaymail After failure

[Timothy White]

Is there any way to configure postfix to use the ISP smtp relay
(relayhost) only when sending directly fails?

For example. 2 Emails that got rejected, one with error code 554[1]
and the other with error code 451 [2]. I prefer to do my own delivery
rather than rely on my ISP...
Look below for a more informative error message.

Thanks

Tim

[1]
to=<cut at iinet.net.au>, relay=filter.iinet.net.au[203.0.178.192],
delay=6470, status=deferred (host filter.iinet.net.au[203.0.178.192]
refused to talk to me: 554 mail-iinet.icp-qv1-irony2.iinet.net.au)

[2]
to=<cut at bigpond.com>, relay=extmail.bigpond.com[144.140.90.13],
delay=432834, status=deferred (host extmail.bigpond.com[144.140.90.13]
said: 451 Mail from this IP address blocked due to DNS block list. (in
reply to
MAIL FROM command))