Just to explanin, that the comment below it's just an IDEA that how this feature could be developed.

Thanks !!

It will be a great improvement. This will work for who allow users to open Anonymous Ticket (Users aren't Registered on GLPI DB), so this will work in these scenarios.

GLPI send an-email with a URL like:

http://glpi.mycompany.com/front/glpisurvey.php?id=YkM678ggggHid8NmpQQ8987668990

When the user click on this link, will open a web page like the example below (This webpage can be opened without user need to do a login on GLPI)

Example (This page was draw on Paint and currently doesn't exist)

And, after user fill the survey, the URL for the survey can be disable or something like that.