[Techtalk] [OT] What's a CID?

[Telsa Gwynne]

On Thu, Mar 25, 2004 at 10:23:58AM +0100 or thereabouts, Dan Richter wrote:
> From time to time I get e-mail (written in HTML) which includes links 
> like this:
> [A HREF="cid:031401Mfadb4$3f3dL708$73380718 at 57W81af70Re"]example.com[/A]
> 
> The text of the link can also be an e-mail address. What is the meaning 
> of that?

Of the "cid" in particular? 

On web-based forums, it's quite common to see "cid" (and "sid"
or something similar too) as part of the URLs to specific parts
of a discussion. I have always assumed that "cid" stands for 
"comment-ID". 

You can see such URLs on Slashdot. However, those URLs do 
not begin with "cid". They are more like 

http://name.of.site/comments.pl?sid=012345&cid=9876

Your example shouldn't go anywhere, because if the browser is
told to go to "cid:long-string-here", it would have to know 
what "cid" means to do anything with it. Usually you see
something like http://, https:// or ftp:// at the start. If
I make a typo on one of those, my browser will complain.
Pasting your example into Lynx tells me:

  Alert!: Unsupported URL scheme!

I have also seen long gibberish "id" strings in spam. "Click
here and get free stuff!" And the "here" is a URL of 
http://spammers'.site/responses#01234567890. The next email
they send will be #01234567891, and then #01234567891. And
when any of those links are followed, the spammers get an
identifiable hit in their logs, look up the email address 
they sent it to and add that address to their "real address 
with someone reading it" list to sell or spam some more.

Not much help, there, but that's all I can think of.

Telsa