The Mail woman, referred to by Phineas as Mrs. Ferguson, appears in the episode "Operation Crumb Cake" and Ginger asks her if she can give back the letter that Isabella sent her. She can't, however, as it's against the law for a mail deliverer to deliver the mail to anyone else but the person it's addressed to. When Isabella tries to distract Phineas, Ferb (on the tower of take out food) alerts Phineas of the mail. Phineas was wondering if his comic book arrived but instead, the letter was sent to him by the mailwoman.