how to make sure that only registered users can send the message?

in wich file?

My code looks like this

<!- Message button -->
       
        <?php if(osc_is_web_user_logged_in()) { ?>
        <?php if(function_exists('im_contact_button')) { im_contact_button(); } ?>
           
        <?php } ?>


        <?php echo veronika_banner('item_sidebar'); ?>

I need to have the button always appear, but only the registered user can send it

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