php 发邮件报错unable to get local issuer certificate

发邮件的时候报错，邮件无法发送：SSL certificate: unable to get local issuer certificate

在Windows下，curl找不到CA证书去验证对方的证书！

方法一：（极度不推荐，不安全）

curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);

方法二：

It's easy to fix (php 5.3.7 or higher) - Download a list file with an up-to-date certificate authorities, and add this setting to your php.ini

“ curl.cainfo=<path-to>cacert.pem ”

from http://stackoverflow.com/questions/17478283/paypal-access-ssl-certificate-unable-to-get-local-issuer-certificate