I managed to solve my own problem with the use of XCLIENT. There isn't a
whole lot of information out there, so maybe search engines will pick up
on this post and help someone else.
It was very easy to set up. Simply turn "xclient off" to "xclient on" in
the nginx configuration as quoted below
Hello,
I started using nginx as a proxy for incoming mail, for DDoS protection
and hiding of origin.
I have it set up as follows:
mail {
server_name foo.bar.com;
auth_http localhost:8080/auth-smtppass.php;
server {
listen 25;
protocol s
