wordpress website email issue

Hello: My vendor always sends me a message via mail when he ships stuff. I need to have the status of the according order switched to done, as soon as the mail arrives. [login to view URL] and whenever this mail arrives ... the order with the number xy (here its #6554) should be looked up in the orders and the order status shall be switched to "done" and a mail shall be sent to . the customer with the according tracking link. this is the text of the message sent Die Bestellung #6554 wurde versendet. A third party is doing the shipping. When the order is sent, the third party plugin sends out a notification to the third party. They send a mail to me whenever I ship stuff. The mail contains a header with the order number in the subject line. In the mail area the mail contains the customer data and the tracking is and a link to the shipping tracking . I need you to write a plugin which is triggered on every day at 17:00. It shall open my new mails in the mailbox and shall verify if there are Any ones with a order number. If there are, these ids should be looked up in the back end and their order status shall be switched from pending to done