I have implemented a nginx with mail module, and proxy to backend Hmail server. I realized no matter how I disable the auth-methods PLAIN. The nginx is just ignoring it.
How can I force to using smtp_auth login instead? As Hmail server does not support AUTH_PLAIN mechanism.
auth_http localhost:8080/auth.pl;
server {
# not working as always AUTH_PLAIN
listen 25;
protocol smtp;
smtp_auth login;
# starttls on;
timeout 5s;
proxy on;
xclient off;
proxy_smtp_auth on;
}