从laravel 5.2应用程序发送来自mailgun的邮件

I am using laravel 5.2 with mailgun. Tried sending an email to a user in order that the user resets password. I get this error

ClientException in RequestException.php line 107: Client error: POST https://api.mailgun.net/v3/sandbox7337ad8917084e1883b28134ba711960.mailgun.org/messages.mime resulted in a 400 BAD REQUEST response: { "message": "Sandbox subdomains are for test purposes only. Please add your own domain or add the address to authoriz (truncated...)

This is a section of my .env file

MAIL_DRIVER=mailgun
MAIL_HOST=smtp.mailgun.org
MAIL_PORT=2525
MAIL_USERNAME=postmaster@sandbox......mailgun.org
MAIL_PASSWORD=mypassword
MAIL_ENCRYPTION=tls

MAILGUN_DOMAIN=sandbox..........mailgun.org
MAILGUN_SECRET=key-.........

config/services.php file

'mailgun' => [
        'domain' => env('MAILGUN_DOMAIN'),
        'secret' => env('MAILGUN_SECRET'),
    ],

config/mail.php file

'driver' => env('MAIL_DRIVER', 'smtp'),
host' => env('MAIL_HOST', 'smtp.mailgun.org'),
'port' => env('MAIL_PORT', 2525),
'from' => ['address' => 'myemail@gmail.com', 'name' => 'myName'],
'encryption' => env('MAIL_ENCRYPTION', 'tls'),
'username' => env('MAIL_USERNAME'),
'password' => env('MAIL_PASSWORD'),
'sendmail' => '/usr/sbin/sendmail -bs',

Please, help.

This is the sandbox domain. You need to verify your own domain or verify the recipient in order to send an email to others.

Follow the link to add recipients: https://mailgun.com/app/testing/recipients