An attorney or the attorney's law firm shall maintain one or more attorney trust accounts for the deposit of funds received from any source for the intended benefit of clients or third persons. The account or accounts shall be maintained in this State, in the District of Columbia, or in a state contiguous to this State, and shall be with an approved financial institution. Unless an attorney maintains such an account, or is a member of or employed by a law firm that maintains such an account, an attorney may not receive and accept funds as an attorney from any source intended in whole or in part for the benefit of a client or third person.