How I can figure out the email address of my contest winners? They all just show "Anonymous"

How I can figure out the email address of my contest winners? They all just show "Anonymous". I need to let them know they've won.

Hi Marie,
Did you collect the E-Mail addresses of your participants?
Do you mean to notify a winning voter or someone who submitted an image?
If you collected the information, you can see those details in the PollUnit's evaluation under "participants" or "options".

Kind regards
Philipp