If in the SMTP Interface of your SMG System, below “External Delivery”, the connection security is at least set to “auto”, the TLS Connections to outbound SHOULD get encrypted whenever possible.

If the target-server responded in his EHLO-Response with STARTTLS as supported, SMG SHOULD have taken the more secure route and started a TLS connection when sending out.

Test wise it might be beneficial to “force TLS" on outbound by setting the external delivery to “STARTTLS” and see what happens, however keep in mind that for regular operation this SHOULD be set back to auto otherwise mail-delivery might fail for “plain” mail servers.

Thank you for the explanation of the individual adjusting screws - I will test this and give you feedback.

Thanks Georg, the playbook to control the settings was perfect. I found the missing setting.

Now the problem is solved.

Thank you, good to hear that the system is now working again as suspected.