How to implement OpenFriends in your own web application

Why?

Implementing the OpenFriends protocol in your application would allow your users to more easily find their friends that are already on your site, or invite them if they aren't. All this without the security concern that always appears when you ask them for their email password. Also, the OpenFriends protocol will not change, while web scraping based solutions will eventually stop working because of changes in the webmail provider. With OpenFriends, instead of mantaining half a dozen different importers for different webmail providers, you can just implement one importer once, and forget about that problem.