Mac Mails: your network preferences prevent content from loading privately

I am currently using Vertura13.0. When I am looking at emails, there are no images loading, and 'Your network preferences prevent content from loading privately' appears on every single emails. I have to click on 'Loading' every time.

Also, I tried Mails Setting -- Privacy -- unticked Protect Mail Activity and Block All Remote Content. After this, it still can't load images automatically.