“WordPress automatically sends an email with the password to new users. How can we disable this feature?”
I’ve seen this question being asked around (e.g. here) and couldn’t find a helpful reply anywhere.
I had this same problem and since I couldn’t find a clean way of doing it I had to comment a line in one of the core files. In the file wp-includes/pluggable.php, function wp_new_user_notification(), you can comment the last line that reads:
wp_mail($user_email, sprintf(__('[%s] Your username and password'), $blogname), $message);
I would love a cleaner way of doing this, if you know one please let me know!
Note that with upgrades you will lose this change. Unfortunately there seems to be no way around this until WordPress supports a filter or some other mechanism to do it in a cleaner way.
Also note that this is different from disabling new user notifications that are sent to the admin email, for that there is an option in the admin panel.
This was done against WordPress Mu 2.9.2. Your mileage may vary of course! :)