my $payload = {
    'sender'        => {
            'name'  => $vars{'fromname'},
            'email' => $vars{'frommail'},
        },
    'to'            => [{
            'name'  => $vars{'name'},
            'email' => $vars{'email'},
        }],
    'subject'       => $vars{'subject'},
    'HTMLcontent'   => $body,
};
$payload->{'textContent'} = $vars{'preview'} if $vars{'preview'};

my $attrs = {
    'headers'   => $headers,
    'content'   => encode_json $payload,
};