Thunderbird disable remote content warning for HTML email

In Thunderbird version 12.01, is there a way to disable the remote content warning that appears in situations such as: when an HTML email wants to load images hosted online?

I expected that the Security tab in Preferences would have an two options: Don't load remote content and Don't warn when an email requests remote content. Not finding this, I went to about:config (config editor) looking for the options. I found

mailnews.message_display.disable_remote_image => true

but settings this to false automatically loads the remote content, which is not the intended outcome.

Is there a way to suppress the prompt to "Show Remote Content" without loading the remote content?

(just as an addendum, I don't want to add contacts to my contact list)

There is a hidden switch for this:

In about:config (Preferences -> Advanced -> Config Editor) look for:

permissions.default.image

change from 1 to 2.