A user is always sent a "confirmation" email in WP - depends on how you define "confirmation". There is no way around it that I have found, outside of modifying core code. This is what WordPress multisite does when you create a new user.
2) Enter username, email, role, and checkbox for "Skip Confirmation Email"
3) click "Add New User" button
This is what happens with "Skip Confirmation Email" unchecked:
1) User is sent an "Activate" account email - the user needs to click the link inside to activate their WP account.
2) User clicks the activate account link
3) User is sent a "New User" email
4) Site admin is sent a "New User Registration" email
This is what happens with "Skip Confirmation Email" checked:
0) With the box checked the user account is automatically registered.
1) User is sent a "New User" email
"Skip Confirmation Email":
UNCHECKED - user gets 2 emails, site admin gets 1 email
CHECKED - user gets 1 email
We didnt want any emails being sent to users or site admin. Unfortunately we couldnt find a plugin method to disable the emails; so we had to make a change to a core file to do so.