wpmu_welcome_notification( int $blog_id, int $user_id, string $password, string $title, array $meta = array() )

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 WP-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 ( $welcome_email == false ) {
		/* translators: Do not translate USERNAME, SITE_NAME, BLOG_URL, PASSWORD: those are placeholders. */
		$welcome_email = __( 'Hello 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 WP-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@' . $_SERVER['SERVER_NAME'];

	$from_name = get_site_option( 'site_name' ) == '' ? 'ClassicPress' : esc_html( get_site_option( 'site_name' ) );
	$message_headers = "From: \"{$from_name}\" <{$admin_email}>\n" . "Content-Type: text/plain; charset=\"" . get_option('blog_charset') . "\"\n";
	$message = $welcome_email;

	if ( empty( $current_network->site_name ) )
		$current_network->site_name = 'ClassicPress';

	/* translators: New site notification email subject. 1: Network name, 2: New site name */
	$subject = __( 'New %1$s Site: %2$s' );

	/**
	 * Filters the subject of the welcome email after site activation.
	 *
	 * @since WP-MU (3.0.0)
	 *
	 * @param string $subject Subject of the email.
	 */
	$subject = apply_filters( 'update_welcome_subject', sprintf( $subject, $current_network->site_name, wp_unslash( $title ) ) );
	wp_mail( $user->user_email, wp_specialchars_decode( $subject ), $message, $message_headers );

	if ( $switched_locale ) {
		restore_previous_locale();
	}

	return true;
}