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Complete Guide to Sending Emails with Multiple Image Captchas Using PHP

M66 2025-06-23

How to Send Emails with Multiple Image Captchas Using PHP

With the growth of the internet, email has become a vital communication tool and plays a key role in identity verification and security. Captchas embedded in emails are particularly important to prevent malicious activities. This article will guide you on how to send emails containing multiple image captchas using PHP, including sample code.

Preparation

The following items are needed to implement this feature:

  1. A server environment supporting PHP;
  2. A PHP mailing library, such as PHPMailer;
  3. The GD library for generating image captchas.

Step 1: Install PHPMailer and GD Library

  1. Install PHPMailer via Composer or download and include the source files in your project;
  2. Ensure the GD library is installed on your server. If not installed, you can run the following command:
<span class="fun">sudo apt-get install php7.4-gd</span>

Step 2: Generate Image Captcha

  1. Create a file named Captcha.php with the captcha generation code;
  2. Use the GD library to draw the captcha image and save the captcha code to the session or database for later verification;
  3. Example code is as follows:
<?php
session_start();
<p>$captcha = imagecreatetruecolor(100, 50);<br>
$bgColor = imagecolorallocate($captcha, 255, 255, 255);<br>
$fontColor = imagecolorallocate($captcha, 0, 0, 0);<br>
$code = rand(1000, 9999);</p>
<p>$_SESSION['captcha'] = $code;</p>
<p>imagefill($captcha, 0, 0, $bgColor);<br>
imagettftext($captcha, 20, 0, 10, 30, $fontColor, 'path/to/font.ttf', $code);</p>
<p>header('Content-Type: image/png');<br>
imagepng($captcha);<br>
imagedestroy($captcha);<br>
?><br>

This is a basic example for generating a captcha. It does not include advanced font effects or interference lines. Adjust according to your needs.

Step 3: Send Email

  1. Create send_email.php to handle email sending;
  2. Include the PHPMailer library and configure SMTP settings;
  3. Add the image captcha as an attachment and send the email;
  4. Sample code is as follows:
<?php
require 'path/to/PHPMailerAutoload.php';
<p>$mail = new PHPMailer;<br>
$mail->isSMTP();<br>
$mail->Host = 'smtp.example.com';<br>
$mail->SMTPAuth = true;<br>
$mail->Username = '<a class="cursor-pointer" rel="noopener">username@example.com</a>';<br>
$mail->Password = 'password';<br>
$mail->SMTPSecure = 'tls';<br>
$mail->Port = 587;</p>
<p>$mail->setFrom('<a class="cursor-pointer" rel="noopener">from@example.com</a>', 'Your Name');<br>
$mail->addAddress('<a class="cursor-pointer" rel="noopener">to@example.com</a>', 'Recipient Name');<br>
$mail->Subject = 'Subject';<br>
$mail->Body = 'This is the HTML message body';</p>
<p>$captcha = 'path/to/captcha.png';<br>
$mail->AddAttachment($captcha);</p>
<p>if (!$mail->send()) {<br>
echo 'Mailer Error: ' . $mail->ErrorInfo;<br>
} else {<br>
echo 'Message sent!';<br>
}<br>
?><br>

Replace path/to/ with your actual file paths.

Step 4: Frontend Page to Display Captcha and Submit Email

  1. Create index.html to show the captcha and email form;
  2. Example code:
<!DOCTYPE html>
<html>
<head>
    <title>Send Email with Captcha</title>
</head>
<body>
    <img src="Captcha.php" alt="Captcha Image">
    <form method="post" action="send_email.php">
        <input type="text" name="captcha" placeholder="Enter Captcha">
        <input type="submit" value="Send Email">
    </form>
</body>
</html>

The page loads the captcha image via . Users enter the captcha and submit the form to trigger email sending.

Summary

This article demonstrates how to use PHP along with PHPMailer and the GD library to send emails containing multiple image captchas. This method effectively enhances email security and is suitable for applications requiring email identity verification. The provided code is simple and easy to understand; you should improve security measures and captcha complexity as needed for your project.

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