Legal Question in Business Law in California

Maybe you can sue in California and let them argue otherwise.

You haven't given us enough information. Where the company is headquartered matters, and so does where it operates. But the proper jurisdiction and venue also depend upon other factors. The most important of these is the nature of the conduct you want to sue over. Specifics of what happened will also matter. Feel free to contact me directly if you want to discuss your case in more detail.

By answering this, I'm assuming that by your use of the word "company" you mean "corporation." If the corporation is a Tennesee corporation, or domiciled in Tennessee, then you could sue in Tennessee, subject to the laws of the state. I cannot give you advice as to the laws of Tennessee, because I am not an attorney licensed to practice in Tennessee, so I suggest you repost in the category for Tennessee lawyers to answer.

Your question is self contradictory in a very important way. You say they do all their business out of Maine, but have their main business address in Tennessee. Those cannot both be true, and "principal place of business" is a key factor in jurisdiction. You also leave out where the company is incorporated, and where the chief officers or owners of the company work. Without that information we can only guess at jurisdiction.