If your Dashboard shows a warning for your contacts that says "contacts have undelivered reminders", it means that one or more of your contacts was sent an sms reminder, and it failed to deliver for various reasons. To resolve the error:
Navigate to your Contacts.
Look for one or more contacts with a warning symbol beside their name. Click that warning symbol.
You will be taken to your sent reminders log, detailing the undelivered reminders for that contact.
Note which reminders were not received by the contact. You may want to resend them, or check the contact's information to ensure accuracy.
Click "Mark Resolved" for each reminder.
The warning will now be resolved.
If you have more questions, please contact us.