i've
postconf mail_version error_notice_recipient
mail_version = 3.10.3
error_notice_recipient = [email protected]
i get, almost exclusively from DigitalOcean IPs, thousands of (e.g.) these
error notices, coming in bursts of 10-20 different payloads
-------- Original Message --------
From: [email protected]
Sent: at Friday, Aug 15, 2025, 10:01 AM EDT
To: [email protected]
Subject: Postfix SMTP server: errors from unknown[161.35.203.43]
> Transcript of session follows.
>
> Out: 220 mx1.example.com ESMTP . All access monitored/recorded.
> In: ??????
> Out: 500 5.5.2 Error: bad UTF-8 syntax
> In:
> Out: 500 5.5.2 Error: bad syntax
> In: ???????'???/???????(̩?0?s?`?r?a?,?v???w??̨?$???
> Out: 500 5.5.2 Error: bad UTF-8 syntax
> In: ???+???????????#
> Out: 500 5.5.2 Error: bad UTF-8 syntax
> In: ??
> Out: 500 5.5.2 Error: bad UTF-8 syntax
> In:
> Out: 500 5.5.2 Error: bad syntax
> In:
> Out: 500 5.5.2 Error: bad syntax
>
> Session aborted, reason: lost connection
>
> For other details, see the local mail logfile
logs are typically
2025-08-14T08:01:24.961952-04:00 svr1
postfix/postscreen-internal/smtpd[35587]: NOQUEUE: lost connection after
CONNECT from unknown[161.35.203.43]
2025-08-14T08:01:24.962394-04:00 svr1 postfix/cleanup[35588]: 4c3P0h6qmcz6X:
message-id=<[email protected]>
2025-08-14T08:01:24.963144-04:00 svr1
postfix/postscreen-internal/smtpd[35587]: disconnect from
unknown[161.35.203.43] commands=0/0
2025-08-14T08:01:24.963198-04:00 svr1 postfix/qmgr[2243]: 4c3P0h6qmcz6X:
from=<[email protected]>, size=832, nrcpt=1 (queue active)
2025-08-14T08:01:25.056583-04:00 svr1 postfix/postscreen[35581]:
CONNECT from [161.35.203.43]:49822 to [xx.xx.xx.xx]:25
2025-08-14T08:01:25.056641-04:00 svr1 postfix/postscreen[35581]: PASS
OLD [161.35.203.43]:49822
2025-08-14T08:01:25.056916-04:00 svr1
postfix/postscreen-internal/smtpd[35587]: connect from unknown[161.35.203.43]
2025-08-14T08:01:25.060865-04:00 svr1 postfix/relay-mx2/smtp[35590]:
Verified TLS connection established to internal.mx2.example.net[10.1.1.50]:25:
TLSv1.3 with cipher TLS_CHACHA20_POLY1305_SHA256 (256/256 bits) key-exchange
x448
2025-08-14T08:01:25.151125-04:00 svr1
postfix/postscreen-internal/smtpd[35587]: NOQUEUE: lost connection after
CONNECT from unknown[161.35.203.43]
2025-08-14T08:01:25.151770-04:00 svr1 postfix/cleanup[35588]: 4c3P0j13w2z6b:
message-id=<[email protected]>
2025-08-14T08:01:25.152408-04:00 svr1
postfix/postscreen-internal/smtpd[35587]: disconnect from
unknown[161.35.203.43] commands=0/0
2025-08-14T08:01:25.152487-04:00 svr1 postfix/qmgr[2243]: 4c3P0j13w2z6b:
from=<[email protected]>, size=992, nrcpt=1 (queue active)
2025-08-14T08:01:25.177114-04:00 svr1 postfix/relay-mx2/smtp[35591]:
4c3P0h5WHhz6Y: to=<[email protected]>,
relay=internal.mx2.example.net[10.1.1.50]:25, delay=0.4, delays=0/0/0.19/0.21,
dsn=2.0.0, status=sent (250 2.0.0 Ok: queued as 4c3P0h6yh1zWgqP)
2025-08-14T08:01:25.177335-04:00 svr1 postfix/qmgr[2243]:
4c3P0h5WHhz6Y: removed
how can the sending of these
"Subject: Postfix SMTP server: errors from unknown[161.35.204.54]"
specific admin notices, be rate limited, or otherwise quieted down? from within
Postfix config?
the logging notification serves a purpose, even if the content isn't
particularly helpful, but these multiples are just unhelpful noise ...
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