I need to configure Postfix to send
451 4.7.0 Temporary problem, please try again later for a specific domain.
I have tried to google for returning custom error codes for a domain with no luck so far.
You should be able to add the domain and desired text to
example.com 451 4.7.0 Temporary problem, please try again later
Remember to run
postmap on it after editing it and reload Postfix.
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