How to filter mail from apple mail?

We have a program written in c# that goes through emails in outlook 2007 and parses out contact information that may be contained in the body of the email or any attachments. What we've found is that any email we get from apple mail, while having legitimate attachments, may also have other attachments that are not the types of files we want to parse. Some of them contain a previous email conversation while others have the signature of the sender. This is problematic because the sender's signature looks like content we'd want to parse but i开发者_StackOverflow中文版n fact we don't want to in this case. So, I'm wondering if there's any way to tell if an email came from apple mail to try and do some type of filtering against them? Thanks.

Look in the X-Mailer header. An example in my inbox looks like this:

X-Mailer: Apple Mail (2.936)