Most likely it is legit. I received one this week also (my second).
Long story short, I purchased a trademark name and used it to point to my affiliate link. As I mentioned in another post, this is my first attempt at this approach.
It worked very well but I did not redirect my traffic - which is what did me in.
The attorney sent me an email with the D&S and log from a previous case identical to mine where the domain owner had to pay 200K in fines.
With some of these, you can just ignore them and remove the links/pages. With this one, they asked that I stop all traffic to their page and GIVE them the domain name. I wrote them back and told them that I would comply but requested that they purchase the domain from me for the price I paid. They got a great deal but at least it is resolved and over with.
Also, be VERY mindful of what you write and say as they will bend it in any way they can if needed. Do not ignore but but take the time to read it as they may be asking you to do something that you can simply stop doing to resolve the issue (as was the case with my first one).
I hope that helps.
Also, now that I think about it... the C&D is most likely tied to the certified letter notice that I received in the mail yesterday. Watch for that as well if they have your correct information.