failed: Invalid argument (os error 22) while attempting to connect to [IP]:25

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1

Trying to inject a message via SMTP (to multiple recipients, one from gmail, the others on self-hosted servers, one to mail-tester.com) - none of the messages arrived. The journalctl log shows:

kumod::egress_source: bind 127.0.0.1 for source:ip-1 failed: Invalid argument (os error 22) while attempting to connect to [2607:f8b0:4023:1::1a]:25

/var/log/kumomta:

{"type":"TransientFailure","id":"3af279bfa42911ee84a7960002cafe7c","sender":"info@psrp.kumo.taskulu.com","recipient":"test-a542kbrbw@srv1.mail-tester.com","queue":"default-tenant@srv1.mail-tester.com","site":"ip-1->reception.mail-tester.com@smtp_client","size":1835,"response":{"code":400,"enhanced_code":null,"content":"KumoMTA internal: failed to connect to any candidate hosts: connect to ResolvedAddress { name: \"reception.mail-tester.com.\", addr: 94.23.206.89 } port 25 and read initial banner: connect to 94.23.206.89:25: Invalid argument (os error 22)","command":null},"peer_address":null,"timestamp":1703621620,"created":1703620748,"num_attempts":0,"bounce_classification":"Uncategorized","egress_pool":"default-pool","egress_source":"ip-1","feedback_report":null,"meta":{"tenant":"default-tenant"},"headers":{"Subject":"Sample email"},"delivery_protocol":"ESMTP","reception_protocol":"ESMTP","nodeid":"2f6489ba-9d9d-47d5-83bb-8492ac3fdd93"}

full error message here: https://paste.mozilla.org/G8tRN1SN

To verify that my server can connect to the mail servers on port 25 I tested with telnet:

root@send:/opt/kumomta/sbin# telnet 94.23.206.89 25
Trying 94.23.206.89...
Connected to 94.23.206.89.
Escape character is '^]'.
220 mail-tester.com ESMTP Postfix (Ubuntu)
2

source_address: Some(127.0.0.1), means that you are binding to the loopback address as the source of your connection. I don’t think you’re going to be able to route that to the public internet

3

you need to use a routeable ip, or just leave it unspecified

4

I think this is the part of the error you are looking for. Make sure your plumbed source IP is listed as the applied source

source:ip-1 failed: Invalid argument (os error 22)

5

Thanks, everything is working now!