Is the waiting period (iddah) required for a wife whose husband abandoned her for four years and then divorced her, and can she marry immediately?

If a man divorces his wife, she must observe the iddah (waiting period), even if he has been absent from her for many long years and has not had sexual relations with her. This is because the iddah is not obligatory except after a divorce, based on the words of Allah Almighty: "And divorced women shall wait by themselves for three menstrual cycles." (Quran 2:228). Marriage before the expiry of the iddah is invalid by consensus. The iddah for a divorced woman is three menstrual cycles for those who menstruate, or three months for those who do not menstruate, or by delivering the child for a pregnant woman.