I'm trying to set up our iPhones to access our email server via our VPN server (Windows Server 2008 RRAS / PPTP). I've had a quick look at related solutions on here, and have come to the understanding that:
1) Exchange push on iPhone works by maintaining a TCP/IP connection to the Exchange server, but will *not* work through a VPN server.
2) MobileMe, Yahoo etc push works by sending a sideband sms over the carrier network telling the iPhone to fetch the new mail from the mail server - not an option in our scenario.
So it appears as though there is no way to get push to work via VPN, is this correct?
Based on this assumption, the best case scenario is to set the iPhones up to fetch mail every 15 mins over VPN, which I can live with. Problem is, I cant get this to work either. I have noticed the following:
1) When on WiFi - The iPhone appears to turn off WiFi whenever it goes to sleep. Have confirmed this by observing failed pings while asleep. As a result, the VPN session gets dropped.
2) When on 3G - VPN session also gets dropped intermittently for reasons unknown.
3) iPhone does not appear to try to restore a VPN session - once its dropped, it must be re-enabled manually.
So where does this leave me with regards to the fetch over VPN scenario? Is it possible?