In order to start troubleshooting you need to classify what kind of non-delivered messages you have:

errors

Messages are marked as delivered to server, but never marked as read

  1. Check if another person is Online (a person needs to come Online to read your messages from Server).
  2. Check if another person has the latest Desktop application or Mobile app with Chat functionality added.

Messages are marked as Non-delivered in the Desktop app

  1. Hit Resend option. If the message is still shown as non-delivered proceed with the next steps.
  2. Check internet connection on your computer.
  3. Check if your Presence status is Online or Busy or On Call (displayed on Avatar in the left-bottom corner of the app screen). If Presence status never comes Online or Busy review the following article on how to fix this issue: Intermedia Unite Desktop App: Always Offline
  4. Perform Logout and repeat Login to the application.

In case the problem is not solved please provide us with the application log file. For more information on how to send logs, review Intermedia Unite Application: Collecting Client Logs.