Synology Docker Gitlab SMTP Godaddy


I am running a Synology DS412+ with upgraded RAM to 4GB. I am using the Synology Docker/Gitlab packages. I am fairly new to the Docker/Container concept and I am looking for help to better my understanding. In this case I have a home modem/router between my ISP and the DS412+. I am using UPnP for the port configurations but I am a bit short in my understanding of how to configure SMTP between my Docker/Gitlab container and my Godaddy email host. Particularly the port from the container via the DS412+ via the router. For example I want to use SSL in my email setup which is on port 465. The default Gitlab install maps port 80 (on the container) to port 30000 (on the NAS) which is forwarded from port (30000) on the modem/router. So I am assuming I need to do a similar setup for port 465 in the Gitlab settings after stopping the container and then map 465 to 465 between the container and the NAS station and then to port 465 on the modem/router? My primary concern is security (which I understand UpNP is not favored for) and my secondary concern of course is proper setup? As of now I cannot send emails from gitlab via Godaddy even though I had configured the environment variables and mapped the ports. Perhaps incorrectly so?