Don't embed images directly
Hey,
we are enterprise customers (if that matters).
We played around with mattermost a while with a small team first and fixed several stuff for our use (mostly small stuff like CSS), but one thing should really have an option in the admin panel (in our opinion).
You should be able to prepend a generic media proxy URL (like https://github.com/atmos/camo) to preview'd media. We ended up hardcoding it, what is not much a problem. But in our opinion embedding images directly is a security risk (ip-leaks, csrf attacks, ...) and also could break ssl.
The preview could use some love in general, but we think this is crucial.
Thank you Tom for the feature proposal!
Mattermost v4.7 and later support an image proxy. You can deploy it with atmos/camo https://github.com/atmos/camo
More information in our docs: https://docs.mattermost.com/administration/image-proxy.html