Yes, I found some tool. I am posting this because I think someone in future who googles down to this thread may find it useful.
There is an option in webmin :-P which lets us read usermail from mbox files and can sort mails depending on:-
and so on
Which we can then download as a file then.
Now I am working on some script that would do the same(If I get enough time)
I really hope this SHOULD help some one else too!