Email images not loading in previews
Sometimes you may not see your email images appear in your previews, ranging from hosting to load speed.
Linking to locally hosted images
Litmus does not provide image hosting, and your images will need to be either hosted on your server or through your Email Service Provider. You may want to check your email's HTML to make sure that you are not using local image links. If your image links are pointing to locally hosted images, then you will want to update these links to your hosted image URLs and then submit a retest.
Images stored within a testing environment or behind a firewall
If your images are hosted within a testing environment or behind a firewall, you can allow requests based on our user agent. We do not use static IPs for our asset retrieval, so allowing a single IP address or range of addresses would likely be ineffective.
When we download preview images, we always pass a user agent along that contains X-Litmus-Image-Check. Many firewalls have the ability to allow requests based on user-agent strings. It's the recommended option as this will be consistent and won't change, unlike IPs.
Partially loaded images within your results
If you see images that have partially loaded or have an email result with one or two unloaded images, you may want to run a recapture for this result. This can be done by clicking on the result and then using the keyboard shortcut 'R' to generate a new screenshot or by using the Recapture image button in Previews & QA under the specific client. This will usually resolve any partially loaded images within your email.
Embedded images in iOS previews
Litmus is unable to support embedded images in iOS previews. Images embedded using Content-ID (CID) tags or base64 encoding will not render in iOS previews and will appear as broken images. There are also several email providers that do not support embedded images and previews will reflect that.
In addition to inconsistent support in inboxes, embedded images increase the overall size of an email which may affect loading time, engagement, and more.