[amy2203]

the mail function:

bool mail ( string $to , string $subject , string $message [, string $additional_headers [, string $additional_parameters ]] )

so you have:
$emailsentto as $to
$subjectOfEmail as $subject
$message as $message
$message2 as $additionalheaders
$headers as $additionalparameters

so your $message2 is moving all of the parameters into the wronf places which is why it doesn't work with it in, but it does without it. You need to combine your $message and $message2 into a single variable to be passed to the mail function.

Try changing to:

//Cleaning Message

$message .= "Products Required";
$message .= "\n\n";
for ($i = 0; $i < $cart["max_cartid"]; $i++){
$message .= "Product Name: ";$message .= $cart["products"][$i]["product"];
$message .= "\n";
$message .= "Product Code: ";$message .= $cart["products"][$i]["productcode"];
$message .= "\n";
$message .= "Quantity: ";$message .= $cart["products"][$i]["amount"];
$message .= "\n\n";
}
$message .= "Cost of products BEFORE SHIPPING: ";$message .= $cart["subtotal"];

$message .= "\n";
$message .= "Customer Details & Address Items to be Shipped to";
$message .= "\n\n";
$message .= "Name: ";$message2 .= $userinfo["b_firstname"];
$message .= $userinfo["b_lastname"];
$message .= "\n";
$message .= "Email: ";$message2 .= $userinfo["email"];
$message .= "\n\n";
$message .= "City: ";$message2 .= $userinfo["b_city"];
$message .= "\n";
$message .= "Country: ";$message2 .= $userinfo["b_countryname"];
$message .= "\n";
$message .= "Post code: ";$message2 .= $userinfo["b_zipcode"];
$message .= "\n\n"; 

you can only assign 1 variable to be the actual message.