Created attachment 552732 [details]
Thunderbird (since version 4) displays blank HTML code for some RSS feeds. Not the whole page is displayed as HTML but only some parts. E.g. the advertisement <div> is in blank HTML instead of rendered.
I tested it on two completely differnent computers.
RSS Settings (translated from German)
- [ ] Show article summary instead of the website
- Menu View --> RSS --> Default (or as website, doesn't matter)
*** This bug has been marked as a duplicate of bug 662907 ***