Reading mails and parsing in outlook

Hi
I need to read all the mails in outlook and to parse the Mail body and
to create a chain of mails. For eg if A writes to B and B to A and
then...
Now i need to parse all the mails and chain mails based on replies.
Wot way it can be done?? Doing thru subject line alone is very risky.
I need to do it with a combination of Message id in message headers
and Mail body and Subject.. Mails may come to corporate users from
mail clients like yahoo, hotmail and that has to be taken into
Account.

Pls suggest me all the possible ways..

Thanks
Anushya