Author: Graeme Fowler Date: To: exim-dev Subject: [exim-dev] [Bug 1066] interpret some 4xx error codes from remote
server as permanent errors (5xx). Sometimes the Postfix MTA returns 4xx
error when mailbox does not exist
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--- Comment #12 from Graeme Fowler <graeme@???> 2011-01-13 14:11:57 ---
(In reply to comment #11) > Then we must not use the "allow_mx_to_ip = yes", "helo_accept_junk_hosts", must
> not receive mail with helo/ehlo without a point (".") (because HELO must be
> FQDN) and so on... Right?
No, not quite.
In the first case, that's clearly a misconfigured domain, which you can choose
to work around.
In the second case, you have the choice to accept mail from whoever you like
with whatever configuration you like.
In the case of modifying response codes - sure, go ahead and do so; however I
believe that it is fundamentally wrong as you *will* end up treating properly
transient failures as permanent and will therefore bounce mail incorrectly. You
have no way of knowing why a remote system is giving you a supposedly transient
error to a condition which the text suggests should be permanent - which is why
the RFC states that the MTA should deal only with the response code, not the
I've said my bit now, and the more I think about it the less I want to shift my
stance. Phil differs with me on this, so I think it's time for some of the
other devs to chime in.