How To Get Contact Email From Submitted Data In Contact Form 7?

I would like to subscribe the user to my other newsletter system using Contact Form 7. I tried to get the recipient email from the submitted form with the below code, but it returns sender (admin) email.

add_action('wpcf7_before_send_mail', function ($contact_form) {
    $mailProp = $contact_form->get_properties('mail');
    subscribe_to_another_newsletter($mailProp['mail']['recipient']);
});

How can I get the contact's data?

You want to grab your submission and then use the form field you used for email to do what you want with it.

add_action( 'wpcf7_before_send_mail', array($this, 'cf7_process_form'));
function my_cf7_process_form(){
    // This calls the static get the cf7 form data
    $submission = WPCF7_Submission::get_instance();
       if ( $submission ) {
        // $posted_data = array with all form fields
        $posted_data = $submission->get_posted_data();    
    }
    // if [your-email] is the form tag
    $email = $posted_data['your-email'];
    subscribe_to_another_newsletter($email);
}