We introduced extra protection to increase the security of surveys. The toggle "Block Anonymous Responses" prevents you from being spammed by fake answers.
How:
1. Check "Block Anonymous Responses" on the Design step of survey creation
2. Make sure all your survey recipients have unique identity attached.
3. All responses from anonymous recipients with no identity will not be recorded if the toggle is enabled.
To add identities, please read article on Adding recipient identities to email embedded survey.
Note: identities are always checked for uniqueness, meaning you don’t have to do this on your own.
Also, it’s worthwhile to use identities rather than properties in order to simplify your data searching, sorting and exporting. Also, properties might impact your analytics overview.
Please keep in mind that unfortunately, we can't retrieve answers sent without recipients if blocking of anonymous answers is turned on. In that case, we don’t process the answer which means it’s not stored in the database or any other system.