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# javax.net.ssl.SSLException: Unsupported or unrecognized SSL message

#### **Version/Environment (if relevant):**

Not version specific

## **Issue:**

After specifying new SMTP settings for email notifications in Central Config a customer failed to receive any notifications. To find more detail we triggered a quick job and tailed the nucleus-dispatcher log. We found an exception occurring. The "caused by" provided a clue:

```
Caused by: javax.net.ssl.SSLException: Unsupported or unrecognized SSL message
at java.base/sun.security.ssl.SSLSocketInputRecord.handleUnknownRecord(SSLSocketInputRecord.java:451)
at java.base/sun.security.ssl.SSLSocketInputRecord.decode(SSLSocketInputRecord.java:175)
at java.base/sun.security.ssl.SSLTransport.decode(SSLTransport.java:110)
at java.base/sun.security.ssl.SSLSocketImpl.decode(SSLSocketImpl.java:1418)
at java.base/sun.security.ssl.SSLSocketImpl.readHandshakeRecord(SSLSocketImpl.java:1324)
at java.base/sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:440)
at java.base/sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:411)
at com.sun.mail.util.SocketFetcher.configureSSLSocket(SocketFetcher.java:626)
at com.sun.mail.util.SocketFetcher.createSocket(SocketFetcher.java:400)
at com.sun.mail.util.SocketFetcher.getSocket(SocketFetcher.java:238)
at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:2175)
... 22 common frames omitted
```

## **Root Cause:**

`javax.net.ssl.SSLException: Unsupported or unrecognized SSL message` can occur if protocols are incorrect. For example if your specify a port that is **NOT** SSL but you chose settings that trying to connect via SSL, this can occur. It is the equivalent of trying to browse https protocol on a webserver port that is only listening for http protocol.

## **Resolution:**

You need to correct either the port or the protocol. Double-check your values for `com.cerebro.domino.email.smtp.ssl` and `com.cerebro.domino.email.channel` and ensure they're aligned with the mailserver's specifications on the port you've designated.

For example if your mailserver administrator told you to use port 25 then you probably need `com.cerebro.domino.email.smtp.ssl=false` rather than true since 25 is usually is not SSL-based.

If your mailserver requires TLS then use:
`com.cerebro.domino.email.smtp.ssl`: false
`com.cerebro.domino.email.smtp.channel`: starttls
and your port would likely be 587 (but confirm with your mailserver admin).

## **Notes/Information:**

Tail dispatcher with timestamps:
kubectl logs deployment.apps/nucleus-dispatcher -n `<your namespace>` --container=nucleus-frontend --follow --timestamps=true


## Related topics

- [Troubleshooting](/knowledge-base/troubleshooting-overview.md)
- [Domino-custom-certificates ConfigMap](/cloud/admin/security-and-compliance/custom-certificates/domino-custom-cert-configmap.md)
- [pip install throws SSL certificate error](/knowledge-base/pip-install-throws-ssl-certificate-error.md)
- ["Invalid host" error when trying to connect MiniO server as a Generic S3 data source](/knowledge-base/invalid-host-error-when-trying-to-connect-minio-server-as-a-generic-s3-data-source.md)