Laravel - 在AJAX CALL中MAIL SEND出现500错误

I am trying to use an ajax call to send a mail in laravel.

AJAX

$(".btn-submit").click(function(e){
    e.preventDefault();

    var name = $("input[name=name]").val();
    var email = $("input[name=email]").val();
    var subject = $("input[name=subject]").val();
    var msg = $("#message").val();

    $.ajax({
       headers: {
        'X-CSRF-TOKEN': $('meta[name="csrf-token"]').attr('content')
       },
       type:'POST',
       url:'/contact',
       data:{name:name, email:email, subject:subject, msg:msg},
       contentType:'application/json',
       success:function(data){
         console.dir(data);
       },
       fail:function(data){
         alert(data);
       }
    });
});

Controller

public function ajaxRequestPost(Request $request){
  $name = $request->input('name');
  $email = $request->input('email');
  $subject = $request->input('subject');
  $msg = $request->input('msg');

  Mail::send('emails.contact-message',[
      'name' => $name,
      'email' => $email,
      'subject' => $subject,
      'msg' => $msg
  ], function($mail) use ($request){
      $mail->from($request->email, $request->name);
      $mail->to('validemail@gmail.com')->subject('Subject');
  });

  return response()->json(['name'=>$name, 'email'=>$email, 'subject'=>$subject, 'msg'=>$msg]);
}

When I use those, I am receiving 500 internal server error. However, I have no idea what is the error with MAIL::SEND, since it works very well in another project Is there something I'm missing?