For surveys and votes where answers are anonymous but each person may answer only once. Under the form's Settings → One response per person, download a set of links (a CSV) and send one to each person. Each link works once. Intake keeps only a fingerprint of each link and whether it has been used, so it cannot tell which link sent which answer, and neither can you.
The hosted page handles the link for you. On your own page, the link's code arrives as ?t= in the address: pass it on by adding it to the endpoint (the settings page has a short script for HTML forms). A post with a missing, unknown or used link gets 403 with "name": "linkUsedError".