wpmu_welcome_notification

	 * @since 3.5.0
	 *
	 * @param int|null $result     The site ID if the site name exists, null otherwise.
	 * @param string   $domain     Domain to be checked.
	 * @param string   $path       Path to be checked.
	 * @param int      $network_id Network ID. Relevant only on multi-network installations.
	 */
	return apply_filters( 'domain_exists', $result, $domain, $path, $network_id );
}

/**
 * Notify a user that their blog activation has been successful.
 *
 * Filter {@see 'wpmu_welcome_notification'} to disable or bypass.
 *
 * Filter {@see 'update_welcome_email'} and {@see 'update_welcome_subject'} to
 * modify the content and subject line of the notification email.
 *
 * @since MU (3.0.0)
 *
 * @param int    $blog_id  Blog ID.
 * @param int    $user_id  User ID.
 * @param string $password User password.
 * @param string $title    Site title.
 * @param array  $meta     Optional. Signup meta data. By default, contains the requested privacy setting and lang_id.
 * @return bool
 */
function wpmu_welcome_notification( $blog_id, $user_id, $password, $title, $meta = array() ) {
	$current_network = get_network();

	/**
	 * Filters whether to bypass the welcome email after site activation.
	 *
	 * Returning false disables the welcome email.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param int|bool $blog_id  Blog ID.
	 * @param int      $user_id  User ID.
	 * @param string   $password User password.
	 * @param string   $title    Site title.
	 * @param array    $meta     Signup meta data. By default, contains the requested privacy setting and lang_id.
	 */
	if ( ! apply_filters( 'wpmu_welcome_notification', $blog_id, $user_id, $password, $title, $meta ) ) {
		return false;
	}

	$user = get_userdata( $user_id );

	$switched_locale = switch_to_locale( get_user_locale( $user ) );

	$welcome_email = get_site_option( 'welcome_email' );
	if ( false == $welcome_email ) {
		/* translators: Do not translate USERNAME, SITE_NAME, BLOG_URL, PASSWORD: those are placeholders. */
		$welcome_email = __(
			'Howdy USERNAME,

Your new SITE_NAME site has been successfully set up at:
BLOG_URL

You can log in to the administrator account with the following information:

Username: USERNAME
Password: PASSWORD
Log in here: BLOG_URLwp-login.php

We hope you enjoy your new site. Thanks!

--The Team @ SITE_NAME'
		);
	}

	$url = get_blogaddress_by_id( $blog_id );

	$welcome_email = str_replace( 'SITE_NAME', $current_network->site_name, $welcome_email );
	$welcome_email = str_replace( 'BLOG_TITLE', $title, $welcome_email );
	$welcome_email = str_replace( 'BLOG_URL', $url, $welcome_email );
	$welcome_email = str_replace( 'USERNAME', $user->user_login, $welcome_email );
	$welcome_email = str_replace( 'PASSWORD', $password, $welcome_email );

	/**
	 * Filters the content of the welcome email after site activation.
	 *
	 * Content should be formatted for transmission via wp_mail().
	 *
	 * @since MU (3.0.0)
	 *
	 * @param string $welcome_email Message body of the email.
	 * @param int    $blog_id       Blog ID.
	 * @param int    $user_id       User ID.
	 * @param string $password      User password.
	 * @param string $title         Site title.
	 * @param array  $meta          Signup meta data. By default, contains the requested privacy setting and lang_id.
	 */
	$welcome_email = apply_filters( 'update_welcome_email', $welcome_email, $blog_id, $user_id, $password, $title, $meta );

	$admin_email = get_site_option( 'admin_email' );

	if ( '' === $admin_email ) {
		$admin_email = 'support@' . wp_parse_url( network_home_url(), PHP_URL_HOST );
	}