email_validation.php

email_validation.php

<?php

// composer require wesbos/burner-email-providers

function validate_email($email)
{
    $email = mb_strtolower($email);

    if(!email_has_valid_format($email)) {
        return "error: invalid email format";
    }

    if(!email_has_valid_domain_record($email)) {
        return "error: invalid email domain";
    }

    if(!email_is_not_in_burner_domains_blacklist($email)) {
        return "error: email domain is disposable / burner provider";
    }

    return true;
}

function get_email_domain($email)
{
    return mb_strtolower(mb_substr(mb_strrchr($email, "@"), 1));
}

function email_has_valid_format($email)
{
    return !empty(filter_var($email, FILTER_VALIDATE_EMAIL));
}

function email_has_valid_domain_record($email)
{
    $domain = get_email_domain($email);

    return checkdnsrr($domain . '.', "MX") || checkdnsrr($domain . '.', "A");
}

function email_is_not_in_burner_domains_blacklist($email)
{
    static $burnersDomains = null;

    if(is_null($burnersDomains)) {
        // @see https://github.com/wesbos/burner-email-providers
        $file = __DIR__ . '/vendor/wesbos/burner-email-providers/emails.txt';
        if(!file_exists($file) || !is_readable($file)) {
            $burnersDomains = [];
        } else {
            $burnersDomains = file($file, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
        }
    }

    if(empty($burnersDomains)) {
        return true;
    }

    $domain = get_email_domain($email);

    return !in_array($domain, $burnersDomains);
}

// OUTPUT:

var_dump(validate_email('foobar')); // error: invalid email format
var_dump(validate_email('@example.com')); // error: invalid email format
var_dump(validate_email('foobar@example')); // error: invalid email format

echo PHP_EOL;

var_dump(validate_email('[email protected]')); // error: invalid email domain
var_dump(validate_email('[email protected]')); // error: invalid email domain
var_dump(validate_email('[email protected]')); // error: error: invalid email domain

echo PHP_EOL;

var_dump(validate_email('[email protected]')); // error: email domain is disposable / burner provider
var_dump(validate_email('[email protected]')); // error: email domain is disposable / burner provider
var_dump(validate_email('[email protected]')); // error: email domain is disposable / burner provider

echo PHP_EOL;

var_dump(validate_email('[email protected]')); // true
var_dump(validate_email('[email protected]')); // true
var_dump(validate_email('[email protected]')); // true