当我尝试使用PHPMailer从gmail发送电子邮件时，我遇到了OpenSSL证书的问题。我怎么能解决这个问题？
2015-10-30 17:12:21 CLIENT -> SERVER: EHLO localhost
2015-10-30 17:12:21 CLIENT -> SERVER: STARTTLS
Warning: stream_socket_enable_crypto(): SSL operation failed with code 1. OpenSSL Error messages: error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed in....location folder.
2015-10-30 17:12:22 SMTP Error: Could not connect to SMTP host.
2015-10-30 17:12:22 CLIENT -> SERVER: QUIT
2015-10-30 17:12:22 SMTP ERROR: QUIT command failed:
2015-10-30 17:12:22 SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting Message could not be sent.Mailer Error: SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting