Upvote:6
The official website of the California Toll Roads is https://thetollroads.com/ (note "the"). There you can verify if the notice is genuine, and if it is, there should be an option to appeal or contest it.
You should carefully check their information about the car involved in the violation; it could be a mistake, or (less likely) that somebody has a fake license plate that matches yours. In the latter case you may also want to report it to the police.