Validation Rules: Valid email, but allow null?

In my app I have 2 email address fields.

The first field is required because it's the main account.

The second field is optional.

Here are my rules currently.

PHP Code:

public $profile = [
    'login_email' => ['label' => 'Login Email', 'rules' => 'required|valid_email'],
    'login_email_2' => ['label' => '2nd Login Email', 'rules' => 'valid_email'] 
]; 


But when I leave the login_email_2 field blank it complains that it's not a valid email.

How can I ignore the valid email rule if the field is blank?

---

I think I solved my own problem with permit_empty

Is there a listing of all the codeigniter validation rules?

I didn't see them singled out in the docs.

Rules for General Use.

Halberd | CodeIgniter Sandbox

You can not have an email that is empty using that rule, you could check it an see if it has a value
in your code then set it to permit_empty and remove the valid_email one check it in your code.

What did you Try? What did you Get? What did you Expect?

Joined CodeIgniter Community 2009.  ( Skype: insitfx )

Rules for General Use.

Thank you!