PHP表单将发送电子邮件，但不发送消息或其他变量

我对PHP非常陌生，所以我不确定我在这里做错了什么。我可以让它发送电子邮件，但它显示为“未知发件人”，并且没有消息。我做错了什么？请帮忙

 <? 

    $userFirstName = $_GET["txtFirstName"];
    $userLastName = $_GET["txtLastName"];
    $userEmail = $_GET["txtEmail"];
    $userPhone = $_GET["txtPhone"];
    $userComment = $_GET["txtComment"];

    $to = "arandomEmail@gmail.com"; 
    $subject = "From randomURL.com"; 
    $email = $_REQUEST['email'] ; 
     $message = $_REQUEST["This message is from " .$userFirstName. " " .$userLastName. ".\n  
                          Their phone number is " .$userPhone. " and has this comment/question: \n" .$userComment. "."] ;
    $headers = "From: $email"; 
    $sent = mail($to, $subject, $message, $headers) ; 

    if($sent) {
        print("Your mail was sent successfully"); 
        } 
    else {
        print "We encountered an error sending your mail"; 
        }
    ?> 

---

该消息不应从$\u请求中提取

$message = "This message is from " .$userFirstName. " " .$userLastName. ".\n  
   Their phone number is " .$userPhone. " and has this comment/question: \n".$userComment. ".";

还要检查您是否真的在$u请求中通过电子邮件发送脚本。这里的假设是您使用POST或GET将其引入。您可以使用

print_r($_REQUEST);

---

该消息不应从$\u请求中提取

$message = "This message is from " .$userFirstName. " " .$userLastName. ".\n  
   Their phone number is " .$userPhone. " and has this comment/question: \n".$userComment. ".";

还要检查您是否真的在$u请求中通过电子邮件发送脚本。这里的假设是您使用POST或GET将其引入。您可以使用

print_r($_REQUEST);

考虑或生产另一个库。考虑或生产另一个库。