with odoo 10 or odoo 11 i could configure the outgoing mailserver with our internal SmartHost.

But with odoo12 i get the following Error while Connection-TEst:

5.5.2 Send hello first

I tested sending emails through Command-line telnet on the odoo-Server-->worked fine. So no misconfiguration of mailserver.

But within odoo since Version 12 it tells an smtp error. Odoo 10/11 also works with identical Settings