你可以使用PHPMailer，它工作得很完美，这里有一个代码示例:

<?php
use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\Exception;

require 'vendor/phpmailer/phpmailer/src/Exception.php';
require 'vendor/phpmailer/phpmailer/src/PHPMailer.php';
require 'vendor/phpmailer/phpmailer/src/SMTP.php';
$editor = $_POST["editor"];
$subject = $_POST["subject"];
$to = $_POST["to"];

try {

    if ($_SERVER["REQUEST_METHOD"] == "POST") {

        $mail = new PHPMailer();
        $mail->IsSMTP();
        $mail->Mailer = "smtp";
        $mail->SMTPDebug  = 1;
        $mail->SMTPAuth   = TRUE;
        $mail->SMTPSecure = "tls";
        $mail->Port       = 587;
        $mail->Host       = "smtp.gmail.com";//using smtp server
        $mail->Username   = "XXXXXXXXXX@gmail.com";//the email which will send the email 
        $mail->Password   = "XXXXXXXXXX";//the password

        $mail->IsHTML(true);
        $mail->AddAddress($to, "recipient-name");
        $mail->SetFrom("XXXXXXXXXX@gmail.com", "from-name");
        $mail->AddReplyTo("XXXXXXXXXX@gmail.com", "reply-to-name");
        $mail->Subject = $subject;
        $mail->MsgHTML($editor);




        if (!$mail->Send()) {
            echo "Error while sending Email.";
            var_dump($mail);
        } else {
            echo "Email sent successfully";
        }
    }
} catch (Exception $e) {
    echo $e->getMessage();
}

我在000webhost上做了以下工作:

$headers  = "MIME-Version: 1.0" . "\r\n";
$headers .= "Content-type: text/html; charset=iso-8859-1" . "\r\n";
$headers .= "From: ". $from. "\r\n";
$headers .= "Reply-To: ". $from. "\r\n";
$headers .= "X-Mailer: PHP/" . phpversion();
$headers .= "X-Priority: 1" . "\r\n";

发送邮件时直接输入邮箱地址:

mail('email@gmail.com', $subject, $message, $headers)

使用“and not”。

这个代码工作，但电子邮件收到了半小时的延迟。

$name = $_POST['name'];
$email = $_POST['email'];
$reciver = '/* Reciver Email address */';
if (filter_var($reciver, FILTER_VALIDATE_EMAIL)) {
    $subject = $name;
    // To send HTML mail, the Content-type header must be set.
    $headers = 'MIME-Version: 1.0' . "\r\n";
    $headers .= 'Content-type: text/html; charset=iso-8859-1' . "\r\n";
    $headers .= 'From:' . $email. "\r\n"; // Sender's Email
    //$headers .= 'Cc:' . $email. "\r\n"; // Carbon copy to Sender
    $template = '<div style="padding:50px; color:white;">Hello ,<br/>'
        . '<br/><br/>'
        . 'Name:' .$name.'<br/>'
        . 'Email:' .$email.'<br/>'
        . '<br/>'
        . '</div>';
    $sendmessage = "<div style=\"background-color:#7E7E7E; color:white;\">" . $template . "</div>";
    // Message lines should not exceed 70 characters (PHP rule), so wrap it.
    $sendmessage = wordwrap($sendmessage, 70);
    // Send mail by PHP Mail Function.
    mail($reciver, $subject, $sendmessage, $headers);
    echo "Your Query has been received, We will contact you soon.";
} else {
    echo "<span>* invalid email *</span>";
}

如果您正在使用SMTP配置来发送电子邮件，请尝试使用PHPMailer。您可以从https://github.com/PHPMailer/PHPMailer下载该库。

我用这种方式创建了我的电子邮件:

function send_mail($email, $recipient_name, $message='')
{
    require("phpmailer/class.phpmailer.php");

    $mail = new PHPMailer();

    $mail->CharSet = "utf-8";
    $mail->IsSMTP();                                      // Set mailer to use SMTP
    $mail->Host = "mail.example.com";  // Specify main and backup server
    $mail->SMTPAuth = true;     // Turn on SMTP authentication
    $mail->Username = "myusername";  // SMTP username
    $mail->Password = "p@ssw0rd"; // SMTP password

    $mail->From = "me@walalang.com";
    $mail->FromName = "System-Ad";
    $mail->AddAddress($email, $recipient_name);

    $mail->WordWrap = 50;                                 // Set word wrap to 50 characters
    $mail->IsHTML(true);                                  // Set email format to HTML (true) or plain text (false)

    $mail->Subject = "This is a Sampleenter code here Email";
    $mail->Body    = $message;
    $mail->AltBody = "This is the body in plain text for non-HTML mail clients";
    $mail->AddEmbeddedImage('images/logo.png', 'logo', 'logo.png');
    $mail->addAttachment('files/file.xlsx');

    if(!$mail->Send())
    {
       echo "Message could not be sent. <p>";
       echo "Mailer Error: " . $mail->ErrorInfo;
       exit;
    }

    echo "Message has been sent";
}

为我解决这个问题的是，一些提供商在使用php邮件时不允许外部收件人:

将代码中的收件人($收件人)更改为本地收件人。这意味着使用来自服务器域的电子邮件地址，例如，如果您的服务器域是www.yourdomain.com，那么收件人的电子邮件地址应该是someone@yourdomain.com。 请上传修改后的php文件，然后重试。 如果仍然不工作:将发件人($sender)更改为本地电子邮件(使用与收件人相同的电子邮件)。 请上传修改后的php文件，然后重试。

希望这能有所帮助! https://www.arclab.com/en/kb/php/how-to-test-and-fix-php-mail-function.html

<?php

$to       = 'name@example.com';
$subject  = 'Write your email subject here.';
$message  = '
<html>
<head>
<title>Title here</title>
</head>
<body>
<p>Message here</p>
</body>
</html>
';

// Carriage return type (RFC).
$eol = "\r\n";

$headers  = "Reply-To: Name <name@example.com>".$eol;
$headers .= "Return-Path: Name <name@example.com>".$eol;
$headers .= "From: Name <name@example.com>".$eol;
$headers .= "Organization: Hostinger".$eol;
$headers .= "MIME-Version: 1.0".$eol;
$headers .= "Content-type: text/html; charset=iso-8859-1".$eol;
$headers .= "X-Priority: 3".$eol;
$headers .= "X-Mailer: PHP".phpversion().$eol;


mail($to, $subject, $message, $headers);

发送HTML电子邮件 在发送电子邮件时，您可以指定Mime版本、内容类型和字符集来发送HTML电子邮件。

例子 上面的例子将发送一个HTML电子邮件消息到name@example.com。您可以对这个程序进行编码，使其能够接收来自用户的所有内容，然后发送电子邮件。