eMail notifications not sent

[BWibo]

I am facing an issue with the latest FME-Server helm chart (fmeserver-2022.2) and eMail notifications.

1. I setup a SMTP server in the server web interface. The SMTP server is correctly configured, I'm 100% sure. I'm using the same setup in another place and explicitly tested the settings again to be sure.

2. The validation of the server succeeds and I save the settings.
   

   After that I get this messages in:
   /resources/logs/core/current/subscribers/core-0_email.log

   Thu-08-Dec-2022 02:32:01.167 PM   INFORM   main   801024 : SMTP Server           : XXXXXX:465
   Thu-08-Dec-2022 02:32:01.168 PM   INFORM   main   801025 : SMTP Account          : XXX@XX.XX
   Thu-08-Dec-2022 02:32:01.168 PM   INFORM   main   801026 : Connection Security   : SSL/TLS
   Thu-08-Dec-2022 02:32:01.169 PM   INFORM   main   801013 : Default Recipients    : {email.to}
   Thu-08-Dec-2022 02:32:01.169 PM   INFORM   main   801017 : Default CC Recipients : {email.cc}
   Thu-08-Dec-2022 02:32:01.170 PM   INFORM   main   801028 : Default BCC Recipients : {email.bcc}
   Thu-08-Dec-2022 02:32:47.630 PM   INFORM   main   801026 : Connection Security   : SSL/TLS
   

3. I run a workflow from the server web interface to test eMail notifications, e.g. samples/austinDownload.fmw.

   

4. The job completes successfully, data can be downloaded:

   

5. No eMail is received and I get this message from:
   /resources/logs/core/current/subscribers/core-0_email.log:

   Thu-08-Dec-2022 02:32:47.630 PM   ERROR    main   801031 : Invalid SMTP server.
   

I tried this out with different SMTP configurations (different servers+accounts, different connection security options SSL or StartTLS (with ports adapted accordingly) and different actions that should trigger an eMail being sent (different workspaces, job types, ...). No success jet.

Any idea on:
a) How to get more information on why sending the eMail fails?
b) Is this a general issue or related to the k8s deployment?