SMTP relay service not working

[Sharath.Gouni]

Hi Team,

We are trying to send email using smtp server which we got it from customer.

But it is not working and we can just seeing access denied error and nothing else.

Log from Zabbix Server after enabling debug mode:
===============
2333978:20230726:115302.444 failed to send email: SSL connect error: error:0A00010B:SSL routines::wrong version number
2333980:20230726:115317.559 failed to send email: An authentication function returned an error
2333988:20230726:115326.330 executing housekeeper
2333988:20230726:115326.450 housekeeper [deleted 5891 hist/trends, 0 items/triggers, 0 events, 0 problems, 0 sessions, 0 alarms, 0 audit, 0 records in 0.118852 sec, idle for 1 hour(s)]
2333979:20230726:115347.461 failed to send email: An authentication function returned an error
2333978:20230726:115432.316 failed to send email: An authentication function returned an error
2333980:20230726:115508.098 failed to send email: Failed sending data to the peer: MAIL failed: 530
2333979:20230726:115711.386 failed to send email: Login denied
2333978:20230726:115744.246 failed to send email: SSL connect error: error:0A00010B:SSL routines::wrong version number
2333980:20230726:115822.875 failed to send email: SSL connect error: error:0A00010B:SSL routines::wrong version number
2333979:20230726:115859.653 failed to send email: SSL connect error: error:0A00010B:SSL routines::wrong version number
===============

Screenshots are attached for the configuration and error.

Could you please help us to understand where it could have gone wrong?

Thanks
Sharath

[Sharath.Gouni]

Attached the screenshots

[Hamardaban]

Try in the server settings specify SSL/TLS and not STARTTLS.
Contact the administration of the mail server and find out the exact connection parameters