need help reverse-proxy config

[itpp2012]

stream {
  limit_conn_zone $binary_remote_addr zone=straddr:10m;

  upstream backendsmtp {
    server smtp1.local:25;
    server smtp2.local:25;
  }

  server {
    listen 2025 ssl;
    error_log  /logging/stream_local_smtp.log debug;
    ssl_certificate /nginx/crts/sdom.cert;
    ssl_certificate_key /nginx/crts/sdom.key;
    include /nginx/conf/sslciphers.conf;
    ssl_session_timeout   60m;
    ssl_handshake_timeout 10s;
    proxy_connect_timeout 10s;
    proxy_timeout 300s;
    proxy_pass backendsmtp;
    limit_conn           straddr 15;
    limit_conn_log_level error;
  }

}

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,271891,271892#msg-271892