I get two of these from double-bounce@ <mymailserver>
Return-Path: <double-bounce@<mymailserver>>
Delivered-To: gerben@<mymailserver>
Received: from <mymailserver>
by snape.rna.nl with LMTP
id /fHmMkhEAWrVGAAAy+4yzw
(envelope-from <double-bounce@<mymailserver>>)
for <gerben@<mymailserver>>; Mon, 11 May 2026 02:51:52 +0000
Received: by <mymailserver> (Postfix)
id CCB1FA290A; Mon, 11 May 2026 02:51:52 +0000 (UTC)
Date: Mon, 11 May 2026 02:51:52 +0000 (UTC)
From: Mail Delivery System <MAILER-DAEMON@<mymailserver>>
To: Postmaster <postmaster@<mymailserver>>
Subject: Postfix SMTP server: errors from unknown[101.47.29.67]
Message-Id: <[email protected]>
Transcript of session follows.
Out: 220 mail.rna.nl
In: EHLO cangrang.cn
Out: 250-snape.rna.nl
Out: 250-PIPELINING
Out: 250-SIZE 25165824
Out: 250-ETRN
Out: 250-STARTTLS
Out: 250-ENHANCEDSTATUSCODES
Out: 250-8BITMIME
Out: 250-DSN
Out: 250 SMTPUTF8
In: STARTTLS
Out: 220 2.0.0 Ready to start TLS
In: EHLO cangrang.cn
Out: 250-snape.rna.nl
Out: 250-PIPELINING
Out: 250-SIZE 25165824
Out: 250-ETRN
Out: 250-AUTH CRAM-MD5
Out: 250-ENHANCEDSTATUSCODES
Out: 250-8BITMIME
Out: 250-DSN
Out: 250 SMTPUTF8
In: MAIL FROM:<[email protected]>
Out: 452 4.3.1 Insufficient system storage
In: QUIT
Out: 221 2.0.0 Bye
Now, I get two of these 2 minutes apart for two different IP-addresses (one
China, one Hong Kong, and this is weird too because my router should block
incoming from China, that is handled by another MX) Anyway, looking in the log,
I see an active spammer being rejected:
May 11 06:59:53 mymailserver smtp_haproxy/postscreen[6992]: CONNECT from
[101.47.29.196]:50413 to [192.168.2.2]:25
May 11 06:59:53 mymailserver postfix/dnsblog[6993]: addr 101.47.29.196 listed
by domain zen.spamhaus.org as 127.0.0.11
May 11 06:59:53 mymailserver postfix/dnsblog[6993]: addr 101.47.29.196 listed
by domain zen.spamhaus.org as 127.0.0.3
May 11 06:59:53 mymailserver smtp_haproxy/postscreen[6992]: DNSBL rank 1 for
[101.47.29.196]:50413
May 11 06:59:58 mymailserver smtp/smtpd[6987]: connect from
unknown[101.47.29.196]
May 11 06:59:59 mymailserver smtp/smtpd[6987]: NOQUEUE: reject: RCPT from
unknown[101.47.29.196]: 450 4.7.1 Client host rejected: cannot find your
reverse hostname, [101.47.29.196]; from=<[email protected]>
to=<[email protected]> proto=ESMTP helo=<qvwendi.cn>
May 11 06:59:59 mymailserver smtp/smtpd[6987]: disconnect from
unknown[101.47.29.196] ehlo=2 starttls=1 mail=1 rcpt=0/1 quit=1 commands=5/6
This is normal stuff in my log. At some point this bad operator was rate
limited. Good. But why do I get the messages from double-bounce@ in this case?
And why is my postfix sending out
452 4.3.1 Insufficient system storage
if it's operating normally (receiving and sending mail and all)?
Gerben Wierda (LinkedIn <https://www.linkedin.com/in/gerbenwierda>, Mastodon
<https://newsie.social/@gctwnl>, Bluesky
<https://bsky.app/profile/gerbenwierda.bsky.social>)
R&A IT Strategy <https://ea.rna.nl/> (main site)
Book: Chess and the Art of Enterprise Architecture <https://ea.rna.nl/the-book/>
Book: Mastering ArchiMate <https://ea.rna.nl/mastering-archimate-edition-3-2/>
YouTube Channel <http://www.youtube.com/@GerbenWierda>
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