Think of it this way. If you're suing me, and you send my attorney a settlement proposal. If you see no evidence that the attorney forwarded it around, a reasonable assumption is that I wrote it off quickly. Don't assume it's definite but it's workable information to inform your decisions on the case.

More to the point, if you see that email has gone to 5 other people in the firm, and an IP address registered to my insurance company, you can infer that they're evaluating it for potential settlement or at least a counter-offer.