BookStackApp/BookStack

class UserInvite extends MailNotification
{
    public $token;

    public function __construct($token)
    {
        $this->token = $token;
    }

    public function toMail($notifiable)
    {
        $appName = ['appName' => setting('app-name')];

        return $this->newMailMessage()
                ->subject(trans('auth.user_invite_email_subject', $appName))
                ->greeting(trans('auth.user_invite_email_greeting', $appName))
                ->line(trans('auth.user_invite_email_text'))
                ->action(trans('auth.user_invite_email_action'), url('/register/invite/' . $this->token));
    }
}

use BookStack\Auth\User;
use BookStack\Notifications\UserInvite;

class UserInviteService extends UserTokenService
{
    protected $tokenTable = 'user_invites';
    protected $expiryTime = 336; // Two weeks

    public function sendInvitation(User $user)
    {
        $this->deleteByUser($user);
        $token = $this->createTokenForUser($user);
        $user->notify(new UserInvite($token));
    }
}