<?php

add_action('future_to_publish', 'send_emails_on_new_event');
add_action('new_to_publish', 'send_emails_on_new_event');
add_action('draft_to_publish' ,'send_emails_on_new_event');
add_action('auto-draft_to_publish' ,'send_emails_on_new_event');


/**
 * Send emails on event publication
 *
 * @param WP_Post $post
 */
function send_emails_on_new_event($post)
{
    $emails = "email_1@mail.com, email_2@mail.com"; //If you want to send to site administrator, use $emails = get_option('admin_email');
    $title = wp_strip_all_tags(get_the_title($post->ID));
    $url = get_permalink($post->ID);
    $message = "Link to post: n{$url}";

    wp_mail($emails, "New post published: {$title}", $message);
}