试试这个:

<?php
$to = "somebody@example.com";
$subject = "My subject";
$txt = "Hello world!";
$headers = "From: webmaster@example.com" . "\r\n" .
"CC: somebodyelse@example.com";

mail($to,$subject,$txt,$headers);
?>

你也可以在https://github.com/PHPMailer/PHPMailer上使用PHPMailer类。

它允许您使用邮件功能或透明地使用smtp服务器。它还可以处理基于HTML的电子邮件和附件，因此您不必编写自己的实现。

这个类是稳定的，它被许多其他项目使用，如Drupal、SugarCRM、Yii和Joomla!

下面是上面页面的一个例子:

<?php
require 'PHPMailerAutoload.php';

$mail = new PHPMailer;

$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 encryption, 'ssl' also accepted

$mail->From = 'from@example.com';
$mail->FromName = '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->WordWrap = 50;                                 // Set word wrap to 50 characters
$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';
}

这是非常基本的方法发送纯文本电子邮件使用邮件功能。

<?php
$to = 'SomeOtherEmailAddress@Domain.com';
$subject = 'This is subject';
$message = 'This is body of email';
$from = "From: FirstName LastName <SomeEmailAddress@Domain.com>";
mail($to,$subject,$message,$from);

使用PHPMailer通过邮件发送用户密码的步骤:

步骤1:首先，从GitHub下载PHPMailer软件包

您只需下载PHPMailer源文件并手动包含所需的文件。

您可以从PHPMailer主页[1]下载带有源代码的ZIP文件， 点击“克隆或下载”绿色按钮(右侧)，然后选择“下载ZIP”。 在要保存源文件的目录中解压缩包。

[1] https://github.com/PHPMailer/PHPMailer

第二步:打开“(来自Gmail地址)谷歌帐户”，执行以下步骤:

禁用谷歌帐号的双因素密码验证。 打开Less Security。 允许第三方应用程序。

步骤3:尝试使用下面的代码(注意:在这里，我只提供了使用PHP和MySQL通过电子邮件发送用户密码的功能代码)

    <?php 
    session_start();

    use PHPMailer\PHPMailer\PHPMailer;  //add use in starting of the code

    $db = mysqli_connect('localhost', 'root', '', '[Enter your Database Name]'); // connect to database

    if (isset($_POST['forgot_btn'])) {
        forgotpassword();
    }

    function forgotpassword(){
    global $db;
     
        $user_id = $_POST['user_id'];
        $result = mysqli_query($db,"SELECT * FROM users where user_id='$user_id'");
        $row = mysqli_fetch_assoc($result);
        $fetch_user_id=$row['user_id'];
        $name=$row['name'];
        $email_id=$row['email_id'];
        $password=$row['password'];
        if($user_id==$fetch_user_id) {
       require '../PHPMailer/vendor/autoload.php';  //Please correctly mention the PHPMailer installed directory (Don't follow my directory)

    $mail = new PHPMailer(TRUE);
    try{
       $mail->setFrom('[Enter your From Email_Address]', '[Enter Sender Name]');
       $mail->addAddress($email_id, $name);  //[To Email Address and Name]
       $mail->Subject = 'Regarding Forgot Password';
       $mail->Body = 'Hi '.$name.',Your Login Password is:'.$password.'';
       $mail->isSMTP();
       $mail->Host = 'smtp.gmail.com';
       $mail->SMTPAuth = TRUE;
       $mail->SMTPSecure = 'tls';
       $mail->Username = '[Enter your From Email_Address]';
       $mail->Password = '[Enter your From Email_Address -> Password]';
       $mail->Port = 587;
       
       if($mail->send())
       {
          echo "<script>alert('Password Sent Successfully');</script>"; 
       }
       else
       {
         echo "<script>alert('Please Check Your Internet Connection or From Email Address/Password or Wrong To Email Address');</script>";   
       }
    }
    catch (Exception $e)
    {
       echo "<script>alert('Please Check Your Internet Connection or From Email Address/Password or Wrong To Email Address');</script>";
    }
        }
    }

    ?>

更多信息请参考这些文档[1]:

[1]. https://alexwebdevelop.com/phpmailer-tutorial/

对于大多数项目，我现在使用Swift mailer。这是一种非常灵活和优雅的面向对象的发送电子邮件的方法，它是由给我们提供流行的Symfony框架和Twig模板引擎的同一个人创建的。

基本用法:

require 'mail/swift_required.php';

$message = Swift_Message::newInstance()
    // The subject of your email
    ->setSubject('Jane Doe sends you a message')
    // The from address(es)
    ->setFrom(array('jane.doe@gmail.com' => 'Jane Doe'))
    // The to address(es)
    ->setTo(array('frank.stevens@gmail.com' => 'Frank Stevens'))
    // Here, you put the content of your email
    ->setBody('<h3>New message</h3><p>Here goes the rest of my message</p>', 'text/html');

if (Swift_Mailer::newInstance(Swift_MailTransport::newInstance())->send($message)) {
    echo json_encode([
        "status" => "OK",
        "message" => 'Your message has been sent!'
    ], JSON_PRETTY_PRINT);
} else {
    echo json_encode([
        "status" => "error",
        "message" => 'Oops! Something went wrong!'
    ], JSON_PRETTY_PRINT);
}

有关如何使用Swift mailer的更多信息，请参阅官方文档。

用这个脚本发送了电子邮件

<h2>Test Mail</h2>
<?php

if (!isset($_POST["submit"]))
  {
  ?>
  <form method="post" action="<?php echo $_SERVER["PHP_SELF"];?>">
  From: <input type="text" name="from"><br>
  Subject: <input type="text" name="subject"><br>
  Message: <textarea rows="10" cols="40" name="message"></textarea><br>
  <input type="submit" name="submit" value="Click To send mail">
  </form>
  <?php
  }

else

  {

  if (isset($_POST["from"]))
    {
    $from = $_POST["from"]; // sender
    $subject = $_POST["subject"];
    $message = $_POST["message"];

    $message = wordwrap($message, 70);

    mail("Test@example.com",$subject,$message,"From: $from\n");
    echo "Thank you for sending an email";
    }
  }
?>

一旦你按下发送电子邮件按钮，电子邮件将被发送到Test@example.com