A participant's email and phone number are shown in their message thread:
Open the Messages tab in your study (top right of the participant screen).
Click into the participant's chat.
Their email and phone number appear near the top right of the thread.
Participant contact details are provided solely for communicating about your research study. Don't add them to mailing lists or use them for anything outside the study.
If you need contact details for many participants at once, see How to export my list of participants.