How can I make an email address clickable in PHP to open the default email program?

To make an email address clickable in PHP to open the default email program, you can use the mailto: protocol in an anchor tag. This will create a clickable link that, when clicked, will open the default email program with the recipient's email address pre-filled.

<?php
$email = "example@example.com";
echo "<a href='mailto:$email'>$email</a>";
?>