reoon_email_validation.php

add_filter('fluentform/validate_input_item_input_email', function ($default, $field, $formData, $fields, $form) {

    // You may change the following 3 lines
    $targetFormId = 101; //change the form id with your own.
    $errorMessage = 'Looks like email is not correct, please use a valid email'; // You may change/modify the meessage
    $apiKey = 'lYlSwj3Uxt5iGecFTHYdqKC4xBQYaClfsss'; //reoon API key, you should use your own api key

    if ($form->id != $targetFormId) {
        return $default;
    }

    $fieldName = $field['name'];
    if (empty($formData[$fieldName])) {
        return $default;
    }
    $email = $formData[$fieldName];


    $response = wp_remote_get('https://emailverifier.reoon.com/api/v1/verify?email='.$email.'&key='.$apiKey.'&mode=quick');
	

    if(is_wp_error($request)) {
        return $default; // request failed so we are skipping validation
    }
	
	$body = json_decode($response['body']);
	
	if($body->status == 'valid'){
		return $default;
	}

   

    return $errorMessage;

}, 10, 5);