Proxy to a local SMTP server via NGINX

[ashish.thorat@freshgravity.com]

I have a requirement to route my SMTP traffic to a local SMTP server via
NGINX on a public facing server. Also, I am using SMTP to route the HTTP
requests on the same server. 

Can someone provide some insights on this, how this can be achieved?

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,283170,283170#msg-283170