Hi @ujtwrujtwr , this is by design.

Some things to consider:

1. danger of spam
2. anonymized survey but admin can check who responded
3. multiple responses from same person, since different tokens

Also, I updated the manual and will add another sentence in the app to match expectations.

From manual https://www.limesurvey.org/manual/Participant_settings :
==Allow public registration==
If you use tokens to control access to your survey, the only people who can use the survey are those who have an entry and a unique token allocated in the survey participants table. If you would like to use tokens, but also allow public registration, set this to "Yes". The "Yes" setting will allow a visitor to register his name and email address. This will create a new entry in your survey participants table for this person, then send them an invitation email. The application's backend ensures that only one person per email address can complete your survey. If a visitor tries to register for the second time with the same email address, they will not receive another email.

Fix committed to master branch: http://bugs.limesurvey.org/plugin.php?page=Source/view&id=39535

@tibor.pacalat
Thank you for the response.

I understand the design intention, and I have also reviewed the manual. However, the issue I am raising is that if the participant deletes the first email, they lose any way to retrieve the tokenized response URL.

If a visitor tries to register for the second time with the same email address, they will not receive another email.

There is no need to issue a different token for the same email address. My suggestion is simply that the exact same email containing the token generated during the first registration should be resent.

This would be a new feature. You can open a feature request if you like.

Maybe a core plugin here ?