I have a solution for GSuite accounts that doesnt have the "@gmail.com" sufix. Also I think it will work for GSuite accounts with the @gmail.com but havent tried it. First you should have the privileges to change the option "allos¿w less secure app" for your GSuite account. If you have the privileges (you can check in account settings->security) then you have to deactivate "two step factor authentication" go to the end of the page and set to "yes" for allow less secure applications. That's all. If you dont have privileges to change those options the solution for this thread will not work. Check https://support.google.com/a/answer/6260879?hl=en to make changes to "allow less..." option.

通过Gmail使用phpMailer库发送邮件 请从Github下载库文件

<?php
/**
 * This example shows settings to use when sending via Google's Gmail servers.
 */
//SMTP needs accurate times, and the PHP time zone MUST be set
//This should be done in your php.ini, but this is how to do it if you don't have access to that
date_default_timezone_set('Etc/UTC');
require '../PHPMailerAutoload.php';
//Create a new PHPMailer instance
$mail = new PHPMailer;
//Tell PHPMailer to use SMTP
$mail->isSMTP();
//Enable SMTP debugging
// 0 = off (for production use)
// 1 = client messages
// 2 = client and server messages
$mail->SMTPDebug = 2;
//Ask for HTML-friendly debug output
$mail->Debugoutput = 'html';
//Set the hostname of the mail server
$mail->Host = 'smtp.gmail.com';
// use
// $mail->Host = gethostbyname('smtp.gmail.com');
// if your network does not support SMTP over IPv6
//Set the SMTP port number - 587 for authenticated TLS, a.k.a. RFC4409 SMTP submission
$mail->Port = 587;
//Set the encryption system to use - ssl (deprecated) or tls
$mail->SMTPSecure = 'tls';
//Whether to use SMTP authentication
$mail->SMTPAuth = true;
//Username to use for SMTP authentication - use full email address for gmail
$mail->Username = "username@gmail.com";
//Password to use for SMTP authentication
$mail->Password = "yourpassword";
//Set who the message is to be sent from
$mail->setFrom('from@example.com', 'First Last');
//Set an alternative reply-to address
$mail->addReplyTo('replyto@example.com', 'First Last');
//Set who the message is to be sent to
$mail->addAddress('whoto@example.com', 'John Doe');
//Set the subject line
$mail->Subject = 'PHPMailer GMail SMTP test';
//Read an HTML message body from an external file, convert referenced images to embedded,
//convert HTML into a basic plain-text alternative body
$mail->msgHTML(file_get_contents('contents.html'), dirname(__FILE__));
//Replace the plain text body with one created manually
$mail->AltBody = 'This is a plain-text message body';
//Attach an image file
$mail->addAttachment('images/phpmailer_mini.png');
//send the message, check for errors
if (!$mail->send()) {
    echo "Mailer Error: " . $mail->ErrorInfo;
} else {
    echo "Message sent!";
}

我尝试了@shasi kanth提供的建议，但没有奏效。我读了文档，做了一些改动。所以我设法通过Gmail使用这段代码发送邮件，其中vendor/autoload.php是由作曲家与作曲家要求“swiftmailer/swiftmailer:^6.0”:

<?php
     require_once 'vendor/autoload.php';
     $transport = (new Swift_SmtpTransport('smtp.gmail.com', 465, 'ssl'))->setUsername ('SendingMail')->setPassword ('Password');

     $mailer = new Swift_Mailer($transport);

     $message = (new Swift_Message('test'))
      ->setFrom(['Sending mail'])
      ->setTo(['Recipient mail'])
      ->setBody('Message')
  ;

     $result = $mailer->send($message);
    ?>

要在Ubuntu中安装PEAR的Mail.php，运行以下命令:

    sudo apt-get install php-pear
    sudo pear install mail
    sudo pear install Net_SMTP
    sudo pear install Auth_SASL
    sudo pear install mail_mime

Gmail需要端口465，它也是来自phpmailer的代码

// Pear Mail Library
require_once "Mail.php";

$from = '<fromaddress@gmail.com>';
$to = '<toaddress@yahoo.com>';
$subject = 'Hi!';
$body = "Hi,\n\nHow are you?";

$headers = array(
    'From' => $from,
    'To' => $to,
    'Subject' => $subject
);

$smtp = Mail::factory('smtp', array(
        'host' => 'ssl://smtp.gmail.com',
        'port' => '465',
        'auth' => true,
        'username' => 'johndoe@gmail.com',
        'password' => 'passwordxxx'
    ));

$mail = $smtp->send($to, $headers, $body);

if (PEAR::isError($mail)) {
    echo('<p>' . $mail->getMessage() . '</p>');
} else {
    echo('<p>Message successfully sent!</p>');
}