If i missed this answer on the docs im sorry. In using address verification it is very clear that any "reject" from the remote mail server would result in the email triggering the verification to be rejected. But i do not see anything about 4xx defer responses. What if the remote server is doing gray listing and responds with a 4xx during the probe process?
How does postfix handle this? Does it also give the email triggering the verification a 4xx or rejects it with a 5xx?
