On 13 Mar 2018, at 22:51 (-0400), li...@lazygranch.com wrote:

I'm getting hit every 10 minutes from this spammer. As you can see I am
rejecting the message. I wonder if the offending email server doesn't
know the message is being rejected?

It's not being rejected, it's being deferred.

Mar 13 23:28:58 centos-1gb-sfo1-01 postfix/smtpd[22153]: NOQUEUE:
reject: RCPT from unknown[113.247.6.67]: 450 4.7.1 Client host
rejected: cannot find your reverse hostname, [113.247.6.67];
from=<sale...@tradepro.net> to=<li...@lazygranch.com> proto=ESMTP
helo=<mail.port25.com>

A '450' response code is explicitly telling the client to try again later.

If you are using reject_unknown_reverse_client_hostname, it is mostly safe to set unknown_client_reject_code to '550' instead of the default '450' but if you are using reject_unknown_client_hostname (which is unsafe for most sites) you should not.

OR: if you don't get any legitimate mail from Hunan, Chongqing, or Hong Kong you can probably safely block 113.240.0.0/12 from talking at all to your SMTP port (or just the /13 to limit it to Hunan.)


--
Bill Cole
b...@scconsult.com or billc...@apache.org
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Currently Seeking Steady Work: https://linkedin.com/in/billcole

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