PHP, mySQL and Outlook/GMail integration

I'm looking to be able to access any email opened in MS Outlook or Gmail and have that email recognised (accessible) from a web application (that will be built). For example, an email is selected that email is tagged programmatically at the tag passed to my application. When the web application is opened, the tag is recognised and the email is launched in either Outlook or Gmail. Please contact me if you have done this sort of work previously.