Here’s an untested example, how you could modify the email body to your needs:
add_filter( 'update_welcome_email',
function( $welcome_email, $blog_id, $user_id, $password, $title, $meta )
{
// Override the email body:
$welcome_email = __( 'Dear User,
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' );
$current_site = get_current_site();
$url = get_blogaddress_by_id($blog_id);
$user = get_userdata( $user_id );
return str_replace(
array( 'SITE_NAME', 'BLOG_TITLE', 'BLOG_URL', 'USERNAME', 'PASSWORD' ),
array( $current_site->site_name, $title, $url, $user->user_login, $password ),
$welcome_email
);
}
, 10, 6 );