what is 'src="cid:'

[phillydog]

I am trying to filter spam, and a bunch of spam that comes through has no text body, but viewing HTML code has the following code fragment:

src="cid:

If I block this, will it cause any negative effects?

 

[xtknight]

Stands for Content ID. I don't think it's dangerous. Maybe you won't be able to see pictures, but I'm not sure.