Where can I check who has participated and who has not?
Participation statistics for email invitations sent can be checked from either Send Survey's tab or Reports tab
Login >> (Select Survey) >> Send Survey >> Sent Items
Please note that the latest email statistics will only be updated when you log out and log back in.
From Reports tab
Login >> (Select Survey) >> Reports >> Participation Statistics
Under "Email Invitation Participant Statistics" you'll find the current email delivery status.
Here under Reports tab, you get Overall and Grouping / Segmentation Participation statistics also.
You can click on the Number Links in the corresponding columns to view the email addresses under that particular column for an Email list.