SMTP outbound timeout

[provokateurin]

When trying to send any email (I tried several different hosts) none of the deliveries succeed and produce roughly these logs:

Oct 27 16:40:33 lyra stalwart-mail[1943505]: 2025-10-27T15:40:33Z INFO Delivery attempt started (delivery.attempt-start) queueId = 271160985029660672, from = "[email protected]", to = ["[email protected]"], size = 353, total = 1
Oct 27 16:40:33 lyra stalwart-mail[1943505]: 2025-10-27T15:40:33Z INFO New delivery attempt for domain (delivery.domain-delivery-start) queueId = 271160985029660672, from = "[email protected]", to = ["[email protected]"], size = 353, total = 1, domain = "univie.ac.at", total = 0
Oct 27 16:40:33 lyra stalwart-mail[1943505]: 2025-10-27T15:40:33Z INFO Fetched TLS-RPT record (tls-rpt.record-fetch) queueId = 271160985029660672, from = "[email protected]", to = ["[email protected]"], size = 353, total = 1, domain = "univie.ac.at", details = ["[email protected]"], elapsed = 22ms
Oct 27 16:40:33 lyra stalwart-mail[1943505]: 2025-10-27T15:40:33Z INFO MTA-STS policy not found (mta-sts.policy-not-found) queueId = 271160985029660672, from = "[email protected]", to = ["[email protected]"], size = 353, total = 1, domain = "univie.ac.at", strict = false, elapsed = 18ms
Oct 27 16:40:38 lyra stalwart-mail[1943505]: 2025-10-27T15:40:38Z INFO Fetching TLSA record (dane.tlsa-record-fetch) queueId = 271160985029660672, from = "[email protected]", to = ["[email protected]"], size = 353, total = 1, domain = "univie.ac.at", hostname = "zidmx4.univie.ac.at", details = "Tlsa { entries: [TlsaEntry { is_end_entity: true, is_sha256: true, is_spki: true, data: [1, 227, 149, 64, 38, 148, 194, 150, 12, 143, 47, 191, 125, 38, 59, 35, 205, 228, 39, 14, 4, 97, 54, 192, 48, 29, 185, 59, 98, 233, 111, 47] }, TlsaEntry { is_end_entity: false, is_sha256: true, is_spki: true, data: [162, 19, 133, 56, 186, 190, 207, 63, 13, 0, 124, 140, 189, 107, 51, 19, 99, 111, 17, 23, 18, 202, 253, 125, 236, 184, 60, 84, 117, 60, 69, 167] }], has_end_entities: true, has_intermediates: true }", strict = false, elapsed = 5138ms
Oct 27 16:42:55 lyra stalwart-mail[1943505]: 2025-10-27T15:42:55Z INFO Connection error (delivery.connect-error) queueId = 271160985029660672, from = "[email protected]", to = ["[email protected]"], size = 353, total = 1, domain = "univie.ac.at", hostname = "zidmx4.univie.ac.at", localIp = (null), remoteIp = 131.130.5.100, remotePort = 25, causedBy = SMTP error occurred (smtp.error) { details = I/O Error, reason = "Connection timed out (os error 110)" }, elapsed = 136451ms

With a ping from the same machine there is absolutely no issue:

ping zidmx4.univie.ac.at
PING zidmx4.univie.ac.at (131.130.5.100) 56(84) bytes of data.
64 bytes from riley.univie.ac.at (131.130.5.100): icmp_seq=1 ttl=54 time=30.7 ms
^C
--- zidmx4.univie.ac.at ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 30.746/30.746/30.746/0.000 ms

My config does not change any of the default timeouts and you can see Stalwart tries to connect for over 2 minutes until it fails.

[andreymal]

ping doesn't mean anything, check the smtp port using something like telnet zidmx4.univie.ac.at 25

[provokateurin]

Ok I see there must be wrong with my setup, as this doesn't work either. Thanks for the pointer 👍

[pepa65]

So what was the issue, outgoing to port 25 blocked?

[provokateurin]

I haven't debugged it yet, but I suspect it is related to my wireguard setup.

[provokateurin]

Ok it's actually not my wireguard, it's https://docs.hetzner.com/cloud/servers/faq/#why-can-i-not-send-any-mails-from-my-server 🤡