当我在localhost中使用gmail smtp发送电子邮件时，返回长消息

I am using PHPmailer library to send email from localhost using wampServer. I am using Gmail SMTP server.I can send email to my deserved mail address. But problem is, after sending the mail I got return message email is sent but at the same time, very long return message also appear and it takes very long time. Why is this long return message along with my return message?

screen shot of the return message

Try this,

$mail->SMTPDebug = 0;

 (0): Disable debugging (you can also leave this out completely, 0 is the default).
 (1): Output messages sent by the client.
 (2): as 1, plus responses received from the server (this is the most useful setting).
 (3): as 2, plus more information about the initial connection - this level can help diagnose STARTTLS failures.
 (4): as 3, plus even lower-level information, very verbose, don't use for debugging SMTP, only low-level problems.