Is Displaying External Messages Safe?

sflorack · 19 Jul 2015, 11:11 PM

It's old news now, but I recently saw this Gmail blog post. If Google is using proxy servers to display external images, does this really make viewing them (by default) somehow safer? It seems a little wishy washy because this Google support answer claims "senders may be able to know whether an individual has opened a message with unique image links". Isn't that the whole purpose of NOT displaying external images in email?

If this truly does make viewing emails safer, does FastMail offer this feature? I've always thought that it would be nice to have the option to enable "Display External Images" on a folder-by-folder basis. Turning it off for the SPAM folder, for example.

BritTim · 19 Jul 2015, 11:29 PM

Fastmail does support this approach: http://blog.fastmail.com/2014/09/16/...mage-proxying/.

It is true that you can block images (or only block images from correspondents not in your address book). That approach has become unpopular. It is inconvenient having to enable display of images on a case by case basis, and most people do not like doing that.

robn · 20 Jul 2015, 02:27 AM

Regarding "sender may know via unique image links", that's not something we can protect against because it would require understanding/guessing what the URL actually means. The proxy does however hide your IP address, browser type and cookies, so it does reduce the amount of information being passed to the image source.

sflorack · 20 Jul 2015, 03:17 AM

Thanks for the reply, Robn and BritTim.

So any chance we can have the "Display External Images" on a folder-by-folder basis, or to at least always default to NOT showing images in the SPAM folder?

robn · 20 Jul 2015, 03:26 AM

Quote:

Originally Posted by sflorack

So any chance we can have the "Display External Images" on a folder-by-folder basis, or to at least always default to NOT showing images in the SPAM folder?

I think folder-by-folder is unlikely, at least right now (mostly configuration UI complexity for a fairly niche feature). Defaulting to not showing on the spam folder seems like a good idea though, and pretty easy to implement. I'll have a chat with the UI team sometime today.

sflorack · 8 Apr 2019, 09:09 PM

I'm only four years late, but I rediscovered this thread going through old action emails.

Thanks for implementing this, FM!

19 Jul 2015, 11:11 PM	#1
sflorack The "e" in e-mail Join Date: Feb 2002 Posts: 2,937	Is Displaying External Messages Safe? It's old news now, but I recently saw this Gmail blog post. If Google is using proxy servers to display external images, does this really make viewing them (by default) somehow safer? It seems a little wishy washy because this Google support answer claims "senders may be able to know whether an individual has opened a message with unique image links". Isn't that the whole purpose of NOT displaying external images in email? If this truly does make viewing emails safer, does FastMail offer this feature? I've always thought that it would be nice to have the option to enable "Display External Images" on a folder-by-folder basis. Turning it off for the SPAM folder, for example.

19 Jul 2015, 11:29 PM	#2
BritTim The "e" in e-mail Join Date: May 2003 Location: mostly in Thailand Posts: 3,090	Fastmail does support this approach: http://blog.fastmail.com/2014/09/16/...mage-proxying/. It is true that you can block images (or only block images from correspondents not in your address book). That approach has become unpopular. It is inconvenient having to enable display of images on a case by case basis, and most people do not like doing that.

20 Jul 2015, 02:27 AM	#3
robn Master of the @ Join Date: May 2012 Location: Melbourne, Australia Posts: 1,007 Representative of: Fastmail.fm	Regarding "sender may know via unique image links", that's not something we can protect against because it would require understanding/guessing what the URL actually means. The proxy does however hide your IP address, browser type and cookies, so it does reduce the amount of information being passed to the image source.

20 Jul 2015, 03:17 AM	#4
sflorack The "e" in e-mail Join Date: Feb 2002 Posts: 2,937	Thanks for the reply, Robn and BritTim. So any chance we can have the "Display External Images" on a folder-by-folder basis, or to at least always default to NOT showing images in the SPAM folder?

8 Apr 2019, 09:09 PM	#6
sflorack The "e" in e-mail Join Date: Feb 2002 Posts: 2,937	I'm only four years late, but I rediscovered this thread going through old action emails. Thanks for implementing this, FM!