You can send in platform messages and resend user invitation using the "Send" drop down in the users tab.
You can send messages to individual users, offices, enterprises and media groups. This is a great tool to use if you want to alert your users to a new course, piece of media, or event. You can also send messages to individual users using the envelope icon next to the user's "edit" button.
Invite Pending Users:
Some users may not register right away using the registration email sent by the "Inviting User" button (see the Adding New Users article). You can see which users have not accepted their invite by viewing their status. If the the status says "pending" then the user has not accepted their invite.
You can quickly resend the registration email to all pending users by clicking on the "Invite pending users" button. This will re-invite ALL pending users.