privacy problem: text/html parts pull in network resources

[Jinwoo Lee]

On Tue, Jan 27, 2015 at 07:47 PM, Daniel Kahn Gillmor <dkg at fifthhorseman.net> wrote:
> On Sun 2015-01-25 12:51:43 -0500, David Bremner wrote:
>> Daniel Kahn Gillmor <dkg at fifthhorseman.net> writes:
>>
>>> If i send a message with a text/html part (either it's only text/html,
>>> or all parts are rendered, or it's multipart/alternative with only a
>>> text/html subpart) and that HTML has <img
>>> src="http://example.org/test.png"/> in it, then notmuch will make a
>>> network request for that image.
>>>
>>> This is a privacy disaster, because it enables an e-mail sender to use
>>> "web bugs" to tell when a given notmuch user has opened their e-mail.
>>
>> I've just pushed Austin's shr related series to master, so this problem
>> should be fixed as of commit b74ed1c. One tradeoff that we should at
>> least remark in NEWS, if not actually fix, is that I think there is now
>> no way to view such images in notmuch.  I don't know offhand what other
>> html renderers will do.
>
> thanks for this, David and Austin!
>
> Other html-rendering mail clients that are privacy-conscious will often
> provide a button or mechanism to indicate that some remote resources
> were requested by the page but weren't fetched (e.g. a button saying
> something like [Load Remote Images...]).  I have no idea who actually
> clicks on those buttons (or why), though, and even if we wanted them,
> we'd only want to add a button on an image that actually had remote
> network resources to load, and i don't know how we'd get that
> information propagated back up the rendering stack to make such a
> display decision.   So i'm fine with leaving it this way for now.

Well, most promotional emails contain remote images and their contents
are incomprehensible without those images.  I ignore most of them but I
do read a few of those promotional emails.  It would be great to have a
UI for loading remote resources.

>
>         --dkg
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