What are some common pitfalls when trying to include additional variables in an email message using PHP?

One common pitfall when including additional variables in an email message using PHP is forgetting to properly concatenate the variables within the email message string. This can result in errors or the variables not being displayed correctly in the email. To solve this issue, make sure to concatenate the variables using the dot (.) operator within the email message string.

// Example of including additional variables in an email message using PHP

$email = "recipient@example.com";
$subject = "Hello, ".$name."!";
$message = "Dear ".$name.",\n\nThank you for your recent purchase of ".$product.". Your order will be shipped to ".$address." soon.";

// Send email
mail($email, $subject, $message);