Please follow the below steps to configure the SMTP mailing process within your server.

1. Click Here to Download Recent phpmailer files.
2. Create php file with below coding.
3. Include PHPMailer Autoload file as like below coding. (This file will change based on phpmailer  version)
   

   Source code

   <?php
   require_once("SMTP_NEW/PHPMailerAutoload.php"); // path to the PHPMailer class
   ?>

4.  Use the below code to implement the Mailing process.
   

   Source code

   <?php
   $mail = new PHPMailer;//$mail->SMTPDebug = 3; // Enable verbose debug output
   $mail->isSMTP(); // Set mailer to use SMTP
   $mail->Host = 'smtp1.example.com;smtp2.example.com'; // Specify main and backup SMTP servers
   $mail->SMTPAuth = true; // Enable SMTP authentication
   $mail->Username = 'user@example.com'; // SMTP username
   $mail->Password = 'secret'; // SMTP password
   $mail->SMTPSecure = 'tls'; // Enable TLS encryption, `ssl` also accepted
   $mail->Port = 587; // TCP port to connect to
   $mail->setFrom('from@example.com', 'Mailer');
   $mail->addAddress('joe@example.net', 'Joe User'); // Add a recipient
   $mail->addAddress('ellen@example.com'); // Name is optional
   $mail->addReplyTo('info@example.com', 'Information');
   $mail->addCC('cc@example.com');
   $mail->addBCC('bcc@example.com');
   $mail->addAttachment('/var/tmp/file.tar.gz'); // Add attachments
   $mail->addAttachment('/tmp/image.jpg', 'new.jpg'); // Optional name
   $mail->isHTML(true); // Set email format to HTML
   $mail->Subject = 'Here is the subject';
   $mail->Body = 'This is the HTML message body <b>in bold!</b>';
   $mail->AltBody = 'This is the body in plain text for non-HTML mail clients';
   if(!$mail->send()) {
   echo 'Message could not be sent.';
   echo 'Mailer Error: ' . $mail->ErrorInfo;
   } else {
   echo 'Message has been sent';
   }
   ?>

5.  Follow the below STEPS to Fix the issue.While we configure it, we have tried with GMAIL SMTP as like below configuration:
   

   Source code

   <?php
   $mail->Mailer = "smtp";
   $mail->SMTPAuth = true; // turn on SMTP authentication
   $mail->SMTPSecure = "ssl"; // OR $mail->SMTPSecure = 'tls';
   $mail->Host = "smtp.gmail.com";
   $mail->Port = 465;
   ?>

6.  But, above settings displayed SMTP connection error. Then, we have tried using Port 587Then, enabled the Debug process using 
   

   Source code

   <?php
   $mail->SMTPDebug = 1;
   ?>

   
    
7.  No help, then we have discussed with server support team to confirm the OPEN PORT and SMTP Configuration details.
8. Finally we have followed below URLs steps to fix the issue. Its related to Google URLs. Its related the enable all access permission to Google SMTP.
   https://accounts.google.com/b/0/DisplayUnlockCaptcha
   https://support.google.com/mail/answer/14257?rd=1

   Allowing less secure apps to access your account:
   https://support.google.com/accounts/answer/6010255
   https://www.google.com/settings/security/lesssecureapps (Access for less secure apps — Turn on)

Need to know below information:
1. While we configure the Gmail SMTP, it not allow to send mail “From ” another email. Like if you configured the SMTP using “xxxx@gmail.com“, sending mail default from address will be same “xxxx@gmail.com“.

If we need to change as client email, we need to create new gmail account with client name OR we need create google App with your domain OR need to configure own SMTP.
Link: https://apps.google.com/
Search keyword: Get gmail for own domain.

We have configured Google APP Once followed below Steps. Also, we could reconfigure it into new server, while changing the server!

1.  Go to Google APPS https://apps.google.com/ and Click “Get Started”.
2. Enter some personal information and create the account.(Select your own User Name and Password)
3. Conform your domain using “Google verification” link “Meta tag” or other method like below option.
   
4. Update the MX record as like below image. We did this in iPage server.
   
   
   Copy the text from below content.(Every one like Copy Paste!)

   Priority	Name | Host | Alias	Value | Destination

5. Delete Existing MX Records within your server settings.Once Configured above steps Google APP worked fine!Then we have migrated the server into new server after some days! So, we have updated the nameserver within domain Manager and Mapped into new server!NOTE: “To find the existing Google APP MX record,  go to Apps > Google Apps > Gmail > User settings. Under MX records,  you could view the current MX records for your primary domain.”

   We need to create same mail ID(primary) with new server using Mail Control panel. And need to configure MX record only. We no need to do all verification steps.

   It will work fine as its before, once transferred the domain into new server!