Lib Validation : permit empty string for valid_email or extend rule

Hello everyone, I want to use validation for mail field which is not required. But empty string is not validated. Is there a method to validate it anyway ?
Or the other option I think is to custom the predefined rule "valid_email", is it possible ?
In advance, thank you.

you can combine it wih other rule. E.g.

$rules = [
'email' => 'permit_empty|valid_email',
];

See https://codeigniter.com/user_guide/libra...eneral-use

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Yes, it works ! Thank you.