Taking information from E-mails and inserting in Spreadsheet

Pretty much what the title says: my friend and I are looking to create a program in C# (if possible! we understand more in C#, but welcome any C++ help if necessary) for a friend/client, who runs a sales business.

This friend sells books over Amazon, as well as in store. He frequently receives E-mail (Gmail/Google-Mail) from Amazon informing him that several of his books have been ordered/dispatched, and is given a stock code, which he then copies into a Microsoft Excel Spreadsheet. The format of the E-mails is always the same, except obviously the name of the book and the unique stock number.

Can anyone help me start this program?