使用 qq 的 smtp 发送邮件,本地测试上正常(国内 ip ),部署到服务器( digitalocean )总是显示 502 错误, nginx 日志显示
[error] 8145#0: *47 upstream prematurely closed connection while reading response header from upstream, client: xxx.xxx.xxx.xxx, server: xxx.com, request: "POST /sign HTTP/1.1", upstream: "http://127.0.0.1:8000/sign", host: "xxx.com", referrer: "http://xxx.com/sign
请教大神这是什么原因,该如何解决