Gnanasekaran Loganathan

Activation mail sent to the new user email once a user registered. The user must activate the account by click activation link in addition to a username and password to log in successfully the first time.
This plugin does not currently work with multi-site. Multi-site uses an activation key system for new registrations already.

User Activation By Email

Require users to click the activation link to access the site which is emailed upon user registration.

paulmac

WordPress allows posting via email, but must be told to check for emails. This is achieved by calling wp-mail.php using either a cron job, or by including a hidden iframe in your blog footer.
This plugin adds the iframe to the blog footer without editing the theme – updating your theme won’t break your ability to email in posts to WordPress.

Email Post Activation

Adds an iFrame to your blog footer to automatically activate any posts written by email.

User Activation By Email vs Email Post Activation