How to configure gmail smtp and phpmailer?

Question

I want to know where the problem is because I get authentication error.

1. I already have a few gmail accounts,
2. I created a new one for my website,
3. I added a new email in "Account and import" to my old gmail account.
4. I copied my new email username and password to phpmailer code

 include_once('phpmailer/class.phpmailer.php'); include_once('phpmailer/class.smtp.php'); //6nb5Drv; function sendmail(){ $mail = new PHPMailer(); $mail->IsSMTP(); // set mailer to use SMTP $mail->SMTPAuth = true; // turn on SMTP authentication $mail->SMTPSecure = "tls"; $mail->Host = "smtp.gmail.com"; // specify main and backup server $mail->Port = 587; // Set the SMTP port i tried and 457 $mail->Username = 'newmail@gmail.com'; // SMTP username $mail->Password = 'newmailpass'; // SMTP password $mail->SMTPDebug = 1; // enables SMTP debug information (for testing) // 1 = errors and messages // 2 = messages only $mail->From = 'from@yahoo.com'; $mail->FromName = 'From'; $mail->AddAddress('to@gmail.com', 'To'); // Add a recipient $mail->IsHTML(true); // Set email format to HTML $mail->Subject = 'Here is the subject'; $mail->Body = 'This is the HTML message body <strong>in bold!</strong>'; $mail->AltBody = 'This is the body in plain text for non-HTML mail clients'; if(!$mail->Send()) { echo 'Message could not be sent.'; echo 'Mailer Error: ' . $mail->ErrorInfo; exit; } echo 'Message has been sent'; } sendmail(); 

But I get an authentication error. What is wrong? Probably something with the credentials, how do I configure gmail smtp?

Debug report:

2015-12-04 17:56:15 CLIENT -> SERVER: EHLO www.site.co 2015-12-04 17:56:15 CLIENT -> SERVER: STARTTLS 2015-12-04 17:56:15 CLIENT -> SERVER: EHLO www.site.co 2015-12-04 17:56:15 CLIENT -> SERVER: AUTH LOGIN 2015-12-04 17:56:15 CLIENT -> SERVER: UHJlZGljdG9sb2d5 2015-12-04 17:56:15 CLIENT -> SERVER: U2dHZlB0VHZUbTZ1SW9ZMi1qTlNCQQ== 2015-12-04 17:56:17 SMTP ERROR: Password command failed: 435 4.7.8 Error: authentication failed: UGFzc3dvcmQ6 2015-12-04 17:56:17 SMTP Error: Could not authenticate. 2015-12-04 17:56:17 CLIENT -> SERVER: QUIT 2015-12-04 17:56:17 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

Answer 1

According to this post: PHPMailer - SMTP ERROR: Password command failed when send mail from my server , in some case, you have to specify google that this is not a suspicious activity and activate some less secure option in your account.
Assuming this is the right password...