How to enable STARTTLS on gocd 21.2.0

[Wojciech Kucjas]

Hello everyone,

I am trying to enable STARTTLS in my gocd server. I have added to my wrapper-properties.conf file mail.smtp.starttls.enable=true line and I have restarted server. Still eveytime when I push
Send Test Email I get " There was an unknown error performing the operation. Possible reason (Not Acceptable) " and in go-server.log i have:

2021-08-06 18:47:22,254 ERROR [Thread-111] GoSmtpMailSender:56 - Sending failed for email [Go Email Notification] to [wojciec...@gmail.com]
com.sun.mail.smtp.SMTPSendFailedException: 530 5.7.0 Must issue a STARTTLS command first

        at com.sun.mail.smtp.SMTPTransport.issueSendCommand(SMTPTransport.java:2358)
        at com.sun.mail.smtp.SMTPTransport.mailFrom(SMTPTransport.java:1823)
        at com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:1300)
        at com.thoughtworks.go.config.GoSmtpMailSender.send(GoSmtpMailSender.java:53)
        at com.thoughtworks.go.config.BackgroundMailSender.lambda$send$0(BackgroundMailSender.java:48)
        at java.base/java.lang.Thread.run(Unknown Source)

Ubuntu 20.04, GO-CD server 21.2.0

Regards,

Wojciech