Is it possible to develop an app similar to the native mail app of iPhone iOS 4 that uses ActiveSync in synchronizing mails and calendar entries?

I understand the native app in the new OS is able to do synchronization. I am wondering if a third party app can also accomplish similar task, has its own settings page where a user can create and configure emails using Exchange server - independent of the OS's native mail and calendar app. Furthermore, is it possible that synchronization be done as soon as a new mail arrives in the server or when a new calendar entry is added. I have tried researching with the keywords {iPHone, sync, activesync} but so far they don't point me to the right direction. I开发者_开发知识库s there an existing app or source code which I can present to my boss as a proof-of-concept? Please help. Thanks.

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ActiveSync: I'm fairly certain Apple had to pay Microsoft to license ActiveSync for use in their code. Their agreement doesn't extend to third-party code and Apple hasn't made it accessible via an API anyway.

Notifications: There is no way for your app to receive notifications in the background. You can use Apple's Push Notification system (if you set up your own server) but if your app is not running then all you can do is update your icon's badge, play a sound, or display an alert. Your code won't execute unless it is already running or the user chooses to launch it in response to a notification.

App Store Approval: Apple doesn't have an explicit ban on 3rd party mail clients, but it's been reported that at least one app (a Gmail client) was rejected for being too similar to the built-in mail client. So unless your app was substantially different than Apple's Mail, it's probably not worth developing.

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Then how is Moxier Mail doing it. They too have Exchange ActiveSync API. Chilkat or MailCore APIs does it using IMAP/POP options but they too do not have Microsoft Exchange Server option to configure. I have used Chilkat and I can develop app almost like Apple Mail app except for Microsoft Exchange setting. So is there any API for having Exchange ActiveSync option too?