php 邮件发送开发前期配置

参考：

https://blog.csdn.net/qq_39666838/article/details/81947225

https://zhidao.baidu.com/question/178447697.html

https://www.cnblogs.com/lxwphp/p/7731250.html

https://www.cnblogs.com/songbo236589/p/8184039.html