nginx 正向代理

stream {
        upstream ms_mail_25 {
            server smtp.office365.com:25;
        }
        server {
            listen 25;
            proxy_connect_timeout 5s;
            proxy_timeout 5s;
            proxy_pass ms_mail_25;
        }
        upstream ms_mail_995 {
            server outlook.office365.com:995;
        }
        server {
            listen 995;
            proxy_connect_timeout 5s;
            proxy_timeout 5s;
            proxy_pass ms_mail_995;
        }
        upstream ms_mail_993{
            server outlook.office365.com:993;
        }
        server {
            listen 993;
            proxy_connect_timeout 5s;
            proxy_timeout 5s;
            proxy_pass ms_mail_993;
        }
        map $ssl_preread_server_name $backend_pool {
            login.microsoftonline.com server_mslogin;
        }
        upstream server_mslogin {
            server login.microsoftonline.com:443;
        }
        server {
            listen 443;
            proxy_connect_timeout 5s;
            proxy_timeout 5s;
            ssl_preread on;
            proxy_pass $backend_pool;
        }