通过lua nginx发送电子邮件超时错误

我正在尝试通过 lua+nginx 发送电子邮件。

Lapis（Lua）代码

local smtp = require("socket.smtp")
app:get("/ee", function(self)

    local from = "<mail0@mydns.name>"
    local rcpt =  {
      "<mail1@gmail.com>"
    }

    local mesgt = {
      headers = {
        to = "PP <mail1@gmail.com>",
        cc = '"V.V." <mail2@gmail.com>',
        subject = "My first message"
      },
      body = "I hope this works. If it does, I can send you another 1000 copies."
    }

    local r, e = smtp.send{
      from = from,
      rcpt = rcpt,
      source = smtp.message(mesgt),
      server = "127.0.0.1",
      port = 25
    }

    return  "R:" .. tostring(r) .. "  E: " .. tostring(e)
end)

会出现超时错误（几秒钟后）："R: nil E: timeout"

Nginx 配置为：

http{
      server{
        listen 9000;
        location = /cgi-bin/nginxauth.cgi {
            add_header Auth-Status OK;
            add_header Auth-Server 127.0.0.1;  # backend ip
            add_header Auth-Port   25;        # backend port
            return 200;
        }
    }

}

mail {
    auth_http         localhost:9000/cgi-bin/nginxauth.cgi;

   server {
        server_name     mydns.name;
        listen          25;
        protocol        smtp;
        proxy           on;
        timeout 5s;
        proxy_pass_error_message on;
        #smtp_auth       login plain;
        xclient         on;
        smtp_auth none;
    }
}

我不理解邮件服务器的核心。如何配置？如何使用 nginx 服务器？我认为超时错误出现是因为邮件服务器只是重定向但不处理电子邮件数据，我是对的吗？或者我需要做什么来修复错误？