Are there any specific guidelines or steps to follow when trying to send HTML emails with PHP to ensure both images and links are included correctly?

When sending HTML emails with PHP, it's important to ensure that images and links are included correctly by using absolute paths for images and setting the correct content types. To include images, use the full URL path to the image in the src attribute of the img tag. For links, make sure to use absolute URLs in the href attribute of the anchor tag.

<?php
$to = "recipient@example.com";
$subject = "HTML Email with Images and Links";
$message = "
<html>
<head>
<title>HTML Email</title>
</head>
<body>
<h1>Hello!</h1>
<p>This is an example HTML email with images and links.</p>
<img src='https://example.com/image.jpg' alt='Image'>
<p>Click <a href='https://example.com'>here</a> for more information.</p>
</body>
</html>
";

$headers = "MIME-Version: 1.0" . "\r\n";
$headers .= "Content-type:text/html;charset=UTF-8" . "\r\n";

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