Issue of Unsupported mail transport [mandrill].

[ashishakya]

I migrated my application from Laravel 5 to Laravel 8
I am using this package ( "intonate/laravel-mandrill-driver": "^2.0") for the transactional email.

But when sending emails, I often get this issue.

my config/services.php looks includes:

return [
.... // other config
   'mandrill' => [
        'secret' => env('MANDRILL_SECRET', ''),
    ],
]

my config/mail.php include

return [
    'driver' => env('MAIL_DRIVER', 'smtp'),
    'host' => env('MAIL_HOST', 'smtp.mailgun.org'),
    'port' => env('MAIL_PORT', 587),
   'from' => [
        'address' => env('MAIL_FROM_ADDRESS', 'default'),
        'name' => env('MAIL_FROM_NAME', 'default'),
    ],
   'username' => env('MAIL_USERNAME'),
    'password' => env('MAIL_PASSWORD'),
    'sendmail' => '/usr/sbin/sendmail -bs',
    "mailers"=>[
        'mandrill' => [
            'transport' => 'mandrill',
        ],
    ]
]

and in .env I'm using keys like

MAIL_DRIVER=mandrill
MAIL_HOST=smtp.mandrillapp.com
MAIL_PORT=587
MAIL_USERNAME="<user_name>"
MANDRILL_SECRET="<mandrill_api_key>"
MAIL_ENCRYPTION=tls