Laravel 5.5 发送邮件错误 : stream_set_blocking() expects parameter 1 to be resource, null given

邮箱配置
MAIL_DRIVER=smtp
MAIL_HOST=smtp.qq.com
MAIL_PORT=25
[email protected]
[email protected]
MAIL_PASSWORD=ytufcmauaykyxxxx
MAIL_ENCRYPTION=tls

用的扩展类发送邮件
UserVerification::send($user, 'confirm email');
本地测试正常，待上传的阿里云虚拟主机上，就报错：
ErrorException (E_WARNING)
stream_set_blocking() expects parameter 1 to be resource, null given