Auto-identify Country Source Of Emails Received Via Software Addin

We are looking for a software or add-in that can be installed within Vista Mail and that would automatically identify the country of origin of each email received... for example by showing a small country flag icon beside each incoming email within our mailbox.

We need to quickly filter spam and competitor emails from certain countries. At present, we do it manually by copy pasting the header of a suspicious mail into a website online that looks up the country of origin for us. So we would like to know of any add-in that automates this process, paid or otherwise, or any alternatives that people are using for this kind of problem.