When someone uploads a picture and then I receive it in email, it always give me an error message when I try to open up the picture they uploaded?

How come when someone uploads a picture and then I receive it in email, it always give me an error message when I try to open up the picture they uploaded?

Hi! You'll only be able to access these uploaded file links if you're signed in to your account. In case you wish to remove this limitation, then please uncheck the privacy option 'Require log-in to view uploaded files.' from your account settings page.

Thank you!