Laravel Mailgun Authentication required issue

I have configure mailgun with my Laravel app. But i am getting the following error when i try to send mail: Swift_TransportException in AbstractSmtpTransport.php line 383: Expected response code 250 but got code "530", with message "530 5.7.1 Authentication required

Here is my .env

MAIL_DRIVER=mailgun
MAIL_HOST=smtp.mailgun.org
MAIL_PORT=587
MAIL_USERNAME=test123@******************************.mailgun.org
MAIL_PASSWORD=*******************
MAIL_ENCRYPTION=tls

MAILGUN_DOMAIN=sandboxdd*********************.mailgun.org
MAILGUN_SECRET=key-******************************

Please Help

via Chebli Mohamed