What are those image tags that appear in Facebook comments and Flickr photo descriptions?

Question

I have seen some strange text in some Facebook comments

Some random comment made by a user followed by some machine generated tag

[cid:[email protected]]

While searching for such pattern in Google, I found that some Flickr photos are also titled in the same pattern.

I think this format is inserted when you reply the FB comments by e-mail and there is an image as signature, but I don't even know if it is possible.

Answer 1

Is it possible to comment using e-mail. When someone has an image signature, the e-mail client can insert this code to refer the image.