coolify/bootstrap/helpers/email.php

<?php

use Illuminate\Support\Str;

function normalize_email_identity(?string $email): ?string
{
    if (blank($email) || ! str_contains($email, '@')) {
        return null;
    }

    [$localPart, $domain] = explode('@', Str::lower(trim($email)), 2);

    if (in_array($domain, ['gmail.com', 'googlemail.com'], true)) {
        $localPart = Str::before($localPart, '+');
        $localPart = str_replace('.', '', $localPart);
    }

    if (blank($localPart) || blank($domain)) {
        return null;
    }

    return $localPart.'@'.$domain;
}