Everything is useful. The only useful thing Microsoft Exchange could do is give us more of a discount on pricing because it's so expensive. Regarding the calendaring functions of Exchange, there is a problem when scheduling an event for the whole day. When you click the whole day event, the scheduling doesn't really work. For example, if I schedule a meeting with you and block your whole day, instead of just putting a time from morning to afternoon, other people can still block your time, which results in double booking. It's kind of a bug that allows people to double-book. So, the scheduling isn't working properly yet. We also faced challenges with backup services. You need to use a third-party backup solution to back up the whole Exchange server properly. You can't use the native Windows backup services. It's like they're forcing me to buy another product, which means additional costs. The backup solution and the double booking issues. If Microsoft Exchange can fix these two things, then it will be very good.