The primary reason an explorer cannot be responded to from within the Gloo platform is that the explorer has not provided a phone number.
If an explorer has not provided a phone number the listed phone number will appear as ***-***-****. In this case you will need to use the provided email address to reach out to the explorer.
Another reason an explorer cannot be responded to is if they have been Rematched to another church. This occurs when the explorer's message was not opened within 16 hours of being routed to you. You will see the Rematched tag next to their name, and their contact information will be gone. Learn more about Rematched explorers here.