Legal Question in Civil Litigation in Arizona

You mean that you have emails acknowledging the debt? This is good. It is called an "admission" at law. There are two parts: (1) They admit something (some amount) is owed but not the exact or full amount and/or (2) they admit the full, exact amount owed. Either (1) or (2) is very powerful. If you have (1) use other evidence e.g. checks, receipts, plus witness testimony, etc. to establish (2), the full amount, including the stated interest or if not agreed to then 10% pre-judgment statutory interest.