Information Security Stack Exchange is a question and answer site for information security professionals. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I am concerned that my computer has been compromised because I sent an email out - but now I noticed that there is a link in the email I did not insert, and I am worried I have a virus or something. I am seeing an invisible image called cleardot.gif appearing next to the sender's name at the bottom of their email. (immediately to the right after "Sincerely, [their name"]). It only happens with this one person. Where does this come from and what is it?

Here's the HTML code:

<img class="" src="">
share|improve this question

closed as off-topic by Xander, NULLZ, TildalWave, Adi, Terry Chia Sep 15 '13 at 3:14

  • This question does not appear to be about Information security within the scope defined in the help center.
If this question can be reworded to fit the rules in the help center, please edit the question.

This question appears to be off-topic because it doesn't appear to be a security question. – Xander Sep 13 '13 at 23:20
If it's not CSS display hack (1x1 pixel images are sometimes required to workaround browser CSS implementation issues); then it is probably a naughty web bug and hence a privacy issue. – LateralFractal Sep 13 '13 at 23:24
Where does it come from? Probably the sender. What is it? Looks like a .gif. – David Houde Sep 14 '13 at 8:51
I'm also seeing this in some e-mails sent from Gmail, although the URL is slightly different now ( I'm fairly sure that the person who sent it to me doesn't have the technical skills to embed such an image link in their e-mails, so presumably it's something automatically injected by Gmail. – Ilmari Karonen Aug 5 '14 at 14:20
Ps. See also this thread on Super User. – Ilmari Karonen Aug 5 '14 at 14:20

Probably a form of "read receipt" verification coming from the sender: Has Your Email Been Read? Read Receipts and Web Bugs

To summarise:

If you need to access internet assets (images, etc) in order to view an email, these assets can be personalised for your instance of the sender's email (e.g. [host]/img/message[uuid].png). If you access the image, the sender knows that you (or your software at least) has read the email.

Privacy controls and filter lists within most email clients can block automatic loading of internet assets in an email. The resulting emails might look ugly but at least your privacy hasn't breached.

Note: The fact that the URL in question doesn't seem unique isn't an issue if this is being done by Google on the behalf of the sender (or themselves); as to fetch the HTTPS asset might require your login cookie, which thus links the image request to you.

share|improve this answer

Not the answer you're looking for? Browse other questions tagged or ask your own question.