Laravel 6 Connection could not be established with host :stream_socket_client(): php_network_getaddresses: getaddrinfo failed: No such host is known

I activate user email verification but I've issues with E-mail Configuration

when I'm trying to send an email I got the error below

Connection could not be established with host server.mydomain.com :stream_socket_client(): php_network_getaddresses: getaddrinfo failed: No such host is known.

.env

MAIL_DRIVER=smtp
MAIL_HOST=server.mydomain.com
MAIL_PORT=465
MAIL_USERNAME=noreplay@mydomain.com
MAIL_PASSWORD=**********
MAIL_ENCRYPTION=tls
MAIL_FROM_ADDRESS=null
MAIL_FROM_NAME="${APP_NAME}"

mail.php

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

'host' => env('MAIL_HOST', 'server.mydomain.com'),

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

'from' => [
    'address' => env('MAIL_FROM_ADDRESS', 'hello@example.com'),
    'name' => env('MAIL_FROM_NAME', 'Example'),
],

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

'username' => env('MAIL_USERNAME','noreplay@mydomain.com    '),

'password' => env('MAIL_PASSWORD','**********'),

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

   'markdown' => [
    'theme' => 'default',

    'paths' => [
        resource_path('views/vendor/mail'),
    ],
],

'log_channel' => env('MAIL_LOG_CHANNEL'),

via Chebli Mohamed