pinalj

<?php
add_action( 'admin_notices', 'my_error_notice' );

function my_error_notice() {
       ?>
       <div class="notice notice-error">
          <p><?php _e( 'There has been an error.', 'my-text-domain' );?></p>
       </div>
       <?php 
}

pinalj

        <div class='notice notice-error'>
            <p>Uh oh! We just received an error.</p>
        </div>
        
        <div class='notice notice-success'>
            <p>This is an awesome way to add notices!</p>
        </div>
        
        <div class='notice notice-info'>
            <p>This is supposed to be some informative text.</p>

pinalj

<?php
/**
 * Handles email sending
 */
class Custom_Email_Manager {

	/**
	 * Constructor sets up actions
	 */
	public function __construct() {