Laravel 5.1 Sending email shows error

i'm trying to send email in laravel 5.1 but getting following error

Class 'Swift_Transport_EsmtpTransport' not found

My code

public function test_mail() {
  $data = ['name' => 'XXX xxx xxx', 'number' => 1234];
  $sent = Mail::send('emails.fee_pay_success', ['data' => $data], function ($m) use ($data) {
        $m->to('abcd@gmail.com', 'Abcd Efg')->subject('Your Reminder!');
    });
 if( ! $sent) dd("something wrong");
dd("send");
}

My config file mail.php

return [

/*
|--------------------------------------------------------------------------
| Mail Driver
|--------------------------------------------------------------------------
|
| Laravel supports both SMTP and PHP's "mail" function as drivers for the
| sending of e-mail. You may specify which one you're using throughout
| your application here. By default, Laravel is setup for SMTP mail.
|
| Supported: "smtp", "mail", "sendmail", "mailgun", "mandrill", "ses", "log"
|
*/

'driver' => env('MAIL_DRIVER', 'smtp'),

/*
|--------------------------------------------------------------------------
| SMTP Host Address
|--------------------------------------------------------------------------
|
| Here you may provide the host address of the SMTP server used by your
| applications. A default option is provided that is compatible with
| the Mailgun mail service which will provide reliable deliveries.
|
*/

'host' => '',

/*
|--------------------------------------------------------------------------
| SMTP Host Port
|--------------------------------------------------------------------------
|
| This is the SMTP port used by your application to deliver e-mails to
| users of the application. Like the host we have set this value to
| stay compatible with the Mailgun e-mail application by default.
|
*/

// 'port' => env('MAIL_PORT', 587), 'port' =>465,

/*
|--------------------------------------------------------------------------
| Global "From" Address
|--------------------------------------------------------------------------
|
| You may wish for all e-mails sent by your application to be sent from
| the same address. Here, you may specify a name and address that is
| used globally for all e-mails that are sent by your application.
|
*/

'from' => ['address' => 'tucell@onlinefeepayment.in', 'name' => 'DU'],

/*
|--------------------------------------------------------------------------
| E-Mail Encryption Protocol
|--------------------------------------------------------------------------
|
| Here you may specify the encryption protocol that should be used when
| the application send e-mail messages. A sensible default using the
| transport layer security protocol should provide great security.
|
*/

//'encryption' => env('MAIL_ENCRYPTION', 'tls'),
'encryption' => 'ssl',

/*
|--------------------------------------------------------------------------
| SMTP Server Username
|--------------------------------------------------------------------------
|
| If your SMTP server requires a username for authentication, you should
| set it here. This will get used to authenticate with your server on
| connection. You may also set the "password" value below this one.
|
*/

'username' => '',

/*
|--------------------------------------------------------------------------
| SMTP Server Password
|--------------------------------------------------------------------------
|
| Here you may set the password required by your SMTP server to send out
| messages from your application. This will be given to the server on
| connection so that the application will be able to send messages.
|
*/

'password' =>'',

/*
|--------------------------------------------------------------------------
| Sendmail System Path
|--------------------------------------------------------------------------
|
| When using the "sendmail" driver to send e-mails, we will need to know
| the path to where Sendmail lives on this server. A default path has
| been provided here, which will work well on most of your systems.
|
*/

'sendmail' => '/usr/sbin/sendmail -bs',

/*
|--------------------------------------------------------------------------
| Mail "Pretend"
|--------------------------------------------------------------------------
|
| When this option is enabled, e-mail will not actually be sent over the
| web and will instead be written to your application's logs files so
| you may inspect the message. This is great for local development.
|
*/

'pretend' => false,

];

via Chebli Mohamed