Hello everybody, I am desperatedly looking for some advice or technical details about using Outlook for Android app. We have just one box with Exchange 2010 SP3 running on Windows 2008 r2 server in internal AD domain (like int-ckp.cz). Internal resources are not accessible from internet, only via Cisco VPN, Echange is not published. Exchange has only selfsigned certificate. Email flow from outside stops in DMZ where postfix handles incoming email and forwards them to Exchange. All mobile devices using Active Sync work fine (after establishing vpn of course). Android and iOS native email clients has no problems, problem arises when users want to use Outlook app for Android or iOS. Outlook app just says "could not connect to server". Is there any comprehensive technical article about what and how does it work, how to set it up ? I have learned that Outlook app does not connect directly to Exchange, but it was difficult for me to capture packets from mobiles and investigate it. Is it DNS related ? Or could it be certificate issue ? Or is it just about opened ports on firewall ? Our security policy does not allow me to open direct access to resources in internal network. Is our scenario technically possible ? Thank you very much for your time and help.