Laravel validation rule to prevent use of email addresses possessing a disposable (blacklisted) domains.

DomainBlackListValidator.php

<?php

// Namespace
namespace App\Validators;

// Using directives
use Cache;
use Carbon\Carbon;

// Domain black list validation class
class DomainBlackListValidator
{

    /**
     * Array of blacklisted domains.
     *
     **/
    private $domains = [];



    /**
     * Retrieve latest selection of blacklisted domains and cache them.
     *
     * @param none.
     * @return void.
     *
     **/
    public function refresh()
    {
        // Define parameters for the cache
        $key = "domains.blacklisted";
        $duration = Carbon::now() -> addMonth();
        $url = "https://raw.githubusercontent.com/ivolo/disposable-email-domains/master/index.json";
		
        // Retrieve blacklisted domains (preferably from the cache)
        $this -> domains = Cache::remember($key, $duration, function() use($url) {
            return json_decode(file_get_contents($url), true); 
        });
    }
	
	

    /**
     * Generate the error message on validation failure.
     *
     * @param string $message.
     * @param string $attribute.
     * @param string $rule.
     * @param array $parameters.
     * @return string.
     *
     **/
    public function message($message, $attribute, $rule, $parameters)
    {
        // Provide custom error message
        return "The $attribute does not allow disposable email (blacklisted) domains.";
    }



    /**
     * Execute the validation routine.
     *
     * @param string $attribute.
     * @param string $value.
     * @param array $parameters.
     * @return bool.
     *
     **/
    public function validate($attribute, $value, $parameters)
    {
        // Load blacklisted domains
        $this -> refresh();

        // Extract domain from supplied email address
        $domain = str_after(strtolower($parameters[0]), "@");
		
        // Run validation check
        return ! in_array($domain, $this -> domains);
    }

}

ValidationServiceProvider.php

<?php

// Namespace
namespace App\Providers;

// Using directives
use Illuminate\Support\ServiceProvider;
use Illuminate\Support\Facades\Validator;

// Validation service provider
class ValidationServiceProvider extends ServiceProvider
{

    /**
     * Bootstrap any application services.
     *
     * @param none.
     * @return void.
     *
     **/
    public function boot()
    {
        // Add custom validation rules
        Validator::extend("blacklist", "App\Validators\DomainBlackListValidator@validate");

        // Add custom validation messages
        Validator::replacer("blacklist", "App\Validators\DomainBlackListValidator@message");
    }



    /**
     * Register any application services.
     *
     * @param none.
     * @return void.
     *
     **/
    public function register()
    {
        //
    }

}