Please help us help you and fill where relevant:
Your LimeSurvey version: 3.28.36+221102
Own server or LimeSurvey hosting: Own
Survey theme/template: N/A
==================
I'm looking for a solution to enforce uniqueness on a short-text question.
For various complicated reasons, I cannot use participant management, but we need to collect email address of the participant via a short text question. I then want to make sure that if that email address has been used, it cannot submitted by another participant. I've read some posts about using AJAX and the LS API to accomplish this... 

Does anyone have a working solution for this?