Godaddy Email on Synology DS412+

Hello,

I am sorry to post questions on a recurring theme which is "email setup" but I have spun my wheels for a very long time and would very much appreciate the help. I have GitLab 10.4.2 installed.

1. I am running a Synology DS412+ with upgraded memory to 4GB
2. I have two sub domains correctly setup pointing to a Synology DDNS url/FQDN
3. The Synology domain and sub domains have/share a security certificate issued by Letsencrypt
4. I use the Synology "NGINX" reverse proxy and load balancing setup to redirect the external requests to the internal GitLab container
5. I can access GitLab from my domains/sub domains both locally and externally (outside my LAN i.e. on "the" WAN)

My relevant email configuration environment variables are:

GITLAB_PORT 80
SMTP_HOST smtpout.secureserver.net (per Godaddy settings)
SMTP_PORT 465 (per Godaddy settings for SSL)
IMAP_USER myusername@mydomain.com
SMTP_STARTTLS false
SMTP_AUTHENTICATION plain
IMAP_SSL false
IMAP_ENABLED true
SMTP_PASS mypassword
IMAP_PASS mypassword
SSL_SELF_SIGNED false
IMAP_HOST imap.secureserver.net
SMTP_USER myusername@mydomain.com
SMTP_DOMAIN www.mydomain.com
SMTP_ENABLED true

Questions:

1. If I am using a load balancer (like NGINX taking in HTTPS requests and then sending them over to the container via HTTP) should email be set to SSL to use port 465 or would it be port 25 etc..?

2. Should I be setting SMTP_TLS=true if I want to use port 465? I understand its default is false.

3. It looks like if I use SMTP_PORT=25 email works. However, when I get the email for resetting my password for example the url in the email has https://gitlab.mydomain.com:80. How do I get rid of the port designation being sent in the email?

4. Are things (emails) still secure this way if I am using SMTP_PORT=25 ? I cannot get email to work with SMTP_PORT=465.

Insights to improve my understanding would be highly appreciated. I have things working but things are not very intuitive yet and I am unclear if this approach is "secure".

Start with the SMTP and IMAP environment variables in the issue, then review how the Synology NGINX reverse proxy forwards HTTPS to the GitLab container over HTTP. Done would require identifying the correct secure SMTP configuration and preventing reset-password URLs from including :80; no source file or test is named.