What you looking is a MIME message parser.
There are some free source code that can do the work for you:
http://mailutilities.codeplex.com/
http://www.codeproject.com/Articles/11882/Advanced-MIME-Parser-Creator-Editor
http://www.codeproject.com/Articles/19777/MIME-Compliant-Parser
and one commercial : http://www.aspnetmime.com/
What you do, is that you give your mail, that actually is a text file, and they return you the parts of your email, like Subject, headers, body, etc...