[Plugin: User Activation Email] Email not sent for activation code

I have multisite installed, by default a mail is sent for user registration, but on one of my blog the theme installed on it has disabled this functionality, so i used your plugin, after activating plugin i don’t see any setting page for plugin, if there is any, but i do see activation code/status in user profile.
I registered a user after activating plugin, and still user signed in just after getting registered as it was happening before activating your plugin.
I can see that user is not in active in user profile page and code is appearing there, but user is also signed in, can you please suggest any solution

http://wordpress.org/extend/plugins/user-activation-email/