Custom Software Enhancements for Microsoft Outlook

I require some software to be written which I can use in conjunction with Microsoft Outlook email. These are custom security rules where under various scenarios a pop up alert will appear on my screen alerting the user to potential issues - this pop up will appear when a user hits "Send" and require the user to click through before sending. I want only experienced freelancers with experience in this area. I want the deliverable software to be easy for me to download and also be written in such a way so that it can easily be added to and amended. I require a freelancer who is available for ongoing work as this could be a project where I require regular enhancements.