Hallo,
ich habe in den Logs meiner beiden Mailcow Instanzen folgendes gesehen:

Beispiel:

Feb 05 19:01:16 mail dockerd[863]: time="2026-02-05T19:01:16.509226837+01:00" level=error msg="[resolver] failed to query external DNS server" client-addr="udp:172.22.1.10:57133" dns-server="udp:172.22.1.254:53" error="read udp 172.22.1.10:57133->172.22.1.254:53: i/o timeout" question=";zt5jhx5s1ni4t9mfkk8a1uqafpn1c58p.uribl.rspamd.com.\tIN\t A"
Feb 05 19:01:16 mail dockerd[863]: time="2026-02-05T19:01:16.511160862+01:00" level=error msg="[resolver] failed to query external DNS server" client-addr="udp:172.22.1.10:40724" dns-server="udp:172.22.1.254:53" error="read udp 172.22.1.10:40724->172.22.1.254:53: i/o timeout" question=";4xxsireryzdgrratnkx948wk91g95rxz.email.rspamd.com.\tIN\t A"
Feb 05 19:01:17 mail dockerd[863]: time="2026-02-05T19:01:17.510374134+01:00" level=error msg="[resolver] failed to query external DNS server" client-addr="udp:172.22.1.10:42110" dns-server="udp:172.22.1.254:53" error="read udp 172.22.1.10:42110->172.22.1.254:53: i/o timeout" question=";zt5jhx5s1ni4t9mfkk8a1uqafpn1c58p.uribl.rspamd.com.\tIN\t A"
Feb 05 19:01:17 mail dockerd[863]: time="2026-02-05T19:01:17.511765504+01:00" level=error msg="[resolver] failed to query external DNS server" client-addr="udp:172.22.1.10:54207" dns-server="udp:172.22.1.254:53" error="read udp 172.22.1.10:54207->172.22.1.254:53: i/o timeout" question=";4xxsireryzdgrratnkx948wk91g95rxz.email.rspamd.com.\tIN\t A"
Feb 05 19:01:18 mail dockerd[863]: time="2026-02-05T19:01:18.511519518+01:00" level=error msg="[resolver] failed to query external DNS server" client-addr="udp:172.22.1.10:39593" dns-server="udp:172.22.1.254:53" error="read udp 172.22.1.10:39593->172.22.1.254:53: i/o timeout" question=";zt5jhx5s1ni4t9mfkk8a1uqafpn1c58p.uribl.rspamd.com.\tIN\t A"
Feb 05 19:01:18 mail dockerd[863]: time="2026-02-05T19:01:18.512954574+01:00" level=error msg="[resolver] failed to query external DNS server" client-addr="udp:172.22.1.10:36832" dns-server="udp:172.22.1.254:53" error="read udp 172.22.1.10:36832->172.22.1.254:53: i/o timeout" question=";4xxsireryzdgrratnkx948wk91g95rxz.email.rspamd.com.\tIN\t A"
Feb 05 19:01:19 mail dockerd[863]: time="2026-02-05T19:01:19.512428928+01:00" level=error msg="[resolver] failed to query external DNS server" client-addr="udp:172.22.1.10:33238" dns-server="udp:172.22.1.254:53" error="read udp 172.22.1.10:33238->172.22.1.254:53: i/o timeout" question=";zt5jhx5s1ni4t9mfkk8a1uqafpn1c58p.uribl.rspamd.com.\tIN\t A"
Feb 05 19:01:19 mail dockerd[863]: time="2026-02-05T19:01:19.513817003+01:00" level=error msg="[resolver] failed to query external DNS server" client-addr="udp:172.22.1.10:60538" dns-server="udp:172.22.1.254:53" error="read udp 172.22.1.10:60538->172.22.1.254:53: i/o timeout" question=";4xxsireryzdgrratnkx948wk91g95rxz.email.rspamd.com.\tIN\t A"

Andere Mailcow ähnlich:

Feb 05 19:01:00 mail dockerd[759]: time="2026-02-05T19:01:00.249730139+01:00" level=error msg="[resolver] failed to query external DNS server" client-addr="udp:172.22.1.10:46853" dns-server="udp:172.22.1.254:53" error="read udp 172.22.1.10:46853->172.22.1.254:53: i/o timeout" question=";zt5jhx5s1ni4t9mfkk8a1uqafpn1c58p.uribl.rspamd.com.\tIN\t A"
Feb 05 19:01:01 mail dockerd[759]: time="2026-02-05T19:01:01.251474212+01:00" level=error msg="[resolver] failed to query external DNS server" client-addr="udp:172.22.1.10:53500" dns-server="udp:172.22.1.254:53" error="read udp 172.22.1.10:53500->172.22.1.254:53: i/o timeout" question=";zt5jhx5s1ni4t9mfkk8a1uqafpn1c58p.uribl.rspamd.com.\tIN\t A"
Feb 05 19:02:15 mail dockerd[759]: time="2026-02-05T19:02:15.349636866+01:00" level=error msg="[resolver] failed to query external DNS server" client-addr="udp:172.22.1.10:38523" dns-server="udp:172.22.1.254:53" error="read udp 172.22.1.10:38523->172.22.1.254:53: i/o timeout" question=";4xxsireryzdgrratnkx948wk91g95rxz.email.rspamd.com.\tIN\t A"
Feb 05 19:02:15 mail dockerd[759]: time="2026-02-05T19:02:15.349763056+01:00" level=error msg="[resolver] failed to query external DNS server" client-addr="udp:172.22.1.10:48147" dns-server="udp:172.22.1.254:53" error="read udp 172.22.1.10:48147->172.22.1.254:53: i/o timeout" question=";zt5jhx5s1ni4t9mfkk8a1uqafpn1c58p.uribl.rspamd.com.\tIN\t A"

Solche Meldungen kommen den ganzen Tag.

Habe viel debuggt aber keinen Fehler gefunden.

docker exec -it mailcowdockerized-unbound-mailcow-1 unbound-control stats_noreset | egrep -i 'num.queries|ratelim|qps|time.now|servfail|timeouts'
thread0.num.queries=31724
thread0.num.queries_ip_ratelimited=0
thread0.num.queries_cookie_valid=0
thread0.num.queries_cookie_client=0
thread0.num.queries_cookie_invalid=0
thread0.num.queries_timed_out=0
total.num.queries=31724
total.num.queries_ip_ratelimited=0
total.num.queries_cookie_valid=0
total.num.queries_cookie_client=0
total.num.queries_cookie_invalid=0
total.num.queries_timed_out=0
time.now=1770324234.036444

In einem älteren Thema hier hat einer als Lösung geschrieben:

/opt/mailcow-dockerized/data/conf/rspamd/local.d/options.inc
dns {
enable_dnssec = true;
timeout = 5;
retransmits = 5;
}

Note to self:
If you increase the DNS timeouts like this, you should also increase the overall rspamd task timeout from 25s…
override.d/worker-normal.inc:task_timeout = 55s

Bevor ich anfange die Container zu verwursten, wollte ich erst mal nachfragen ob es diesbezüglich neue Erkenntnisse gibt.

MfG