List inactive users
With this new feature the portal admins can easily filter out the inactive users and send them a reminder or deactivate if needed. In the user management section where all the users are listed, you have the new option of selecting inactive users who have not logged in more than three months. For that choose "Select" and then "Users inactive since 3 months."
Check the boxes and save the selection in a new "tag" so you can use the other portal feature "Send e-mail to users by selected tag".