The attorney can be contacted to discuss the matter. It cannot be said for certain whether that will stop the filing of a lawsuit, if it has not already been filed. Generally, the matter will come down to whether the debt can be paid.
You can certainly contact the attorney but the letter may all be a scare tactic.
Whether it is "legit" depends on if the law firm is in state or out of state. Only an attorney licensed in your state can file a suit against you on behalf of the plaintiff. Some law firms are nothing more than glorified collection agencies. If the law firm is from out of state, then it is unlikely that lawsuit is imminent...