If you get a 403 error or your images are not accessible from our servers, please check if you, your hosting provider, or your CDN provider have a security plugin or a firewall which prevents our servers from accessing your images. If this is the case, please whitelist our IPs:
136.243.103.55
176.9.77.187
176.9.21.94
176.9.21.54
23.88.6.90
188.40.16.97
These IPs are also available as a JSON here.
You may also need to whitelist the above mentioned IPs if you are using ShortPixel Adaptive Images or Autoptimize's Image Optimization, and notice that the images are served from their original location with a redirect instead of being served from our CDN.