On firefox 45, remote images are not shown in the webmail because of the CSP:

```
Content Security Policy: The page's settings blocked the loading of a resource at https://sendy.nitrokey.com/uploads/1431348652.png ("img-src https://mail.fripost.org").
```

Oh wait, that's weird: it seems to block data-urls too:

```
Content Security Policy: The page's settings blocked the loading of a resource at data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw== ("img-src https://mail.fripost.org").
```

I'm not too excited about allowing browsers to load images from arbitrary sources, but [did it anyway](https://git.fripost.org/fripost-ansible/commit/?id=c90ae1fe9d40a0271844d321a7a54ee219735ccf) with the hope that roundcube's anti-XSS filter is good enough.
I've also checked with the [Email Privacy Tester](https://emailprivacytester.com/) that other external resources blocked by the CSP are probably malicious.
[[closed]]. -- [[guilhem]]