用whmcs邮件发不了

我全新安装的一个裸whmcs发邮件，smtp，打开debug模式，报错发不出去，环境是nginx+mysql5.5+php5.6+ionCube  
我随便换了一个lnmp，一样也是nginx+mysql5.5+php5.6+ionCube就可以发出去，都是裸装whmcs只配置mail参数。
我是7月7日安装的环境，报错信息是：2017-07-07 01:41:49 Connection: opening to ssl://hwsmtp.exmail.qq.com:465, timeout=300, options=array ( ) 2017-07-07 01:41:49 Connection: Failed to connect to server. Error number 2. “Error notice: stream_socket_client(): SSL operation failed with code 1. OpenSSL Error messages: error:14090086:SSL routines:ssl3_get_server_certificate:certificate verify failed 2017-07-07 01:41:49 Connection: Failed to connect to server. Error number 2. “Error notice: stream_socket_client(): Failed to enable crypto 2017-07-07 01:41:49 Connection: Failed to connect to server. Error number 2. “Error notice: stream_socket_client(): unable to connect to ssl://hwsmtp.exmail.qq.com:465 (Unknown error) 2017-07-07 01:41:49 SMTP ERROR: Failed to connect to server: (0) 2017-07-07 01:41:49 SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting