Of the PDC slides I mentioned a couple of days ago DAT316 - Future Directions: Developing Custom Applications using the new Exchange 12 API's - caught my attention. Just out of curiosity really. I doubt if we will move from Extended MAPI to these web service API's on the product I work on. It took a huge effort get to a point where we could use MAPI reliably because of problems with the implementation of the MAPI API, not to mention poor performance, and moving to the new API's would involve an unquantifiable risk that a similar investment might be required. It would be interesting to meet up with developers of other Exchange-based unified messaging products and discuss how they have addressed the issues of getting information in and out of the Exchange message store.