Class 'Swift_Mime_Headers_UnstructuredHeader' not found in Laravel 5.4 - php

Question

I am sending e-mails from Laravel app, the e-mail is working fine in localhost, but not working in production server.
Note: Hosted the application in Shared Hosting (as its for personal use)
My Controller
public function createapplication(Request $request)
{
$leaves = Application::create([
'emp_id' => auth()->user()->id,
'from_date' => request('from_date'),
'to_date' => request('to_date'),
'days' => request('days'),
'reason' => request('reason')
]);
$fromdate = $request->from_date;
$to_date = $request->to_date;
$days = $request->days;
$reason = $request->reason;
$data = array(
'name' => auth()->user()->name,
'From_date' => $fromdate,
'To_date' => $to_date,
'Days' => $days,
'Reason' => $reason
);
Mail::send('mail.leavesmail', $data, function($message) use ($fromdate, $to_date, $days, $reason)
{
$message->to('example.com', 'example')->subject('Leave Application');
$message->from('example.com', "example");
$message->cc(auth()->user()->email);
});
return redirect()->back()->with('status', 'Leave Application Submitted Successfully!');
}

Answer 1

For personal use or not, using your own host to send mail is generally a bad idea. There are many problems that you may come across from not being able to send mail (Host disables mail sending to stop spam). Mail going into spam (Mail comes from a known spam IP) among other issues. For this reason I would suggest Mailgun, it's free tier will keep you going forever.
Onto the problem itself, have you run composer install it looks as if a class is just missing due to that?