Deactivate HTML display in incoming emails in Thunderbird
I do not believe you can stop the rendering itself.
The 3 things I know of that you can use are...
- View > Message Body As > Plain text
- Not use preview (f8 toggles on/off)
- You can also enable Tools > Options > Advanced > Privacy > Block loading of remote images to stop loading remote images (that also kills the ability to execute code from there).