Z-Push/MS ActiveSync original platform specific issue Outlook 2016

  • Hello Community!

    I’ve an interesting question based on my recent observation.
    The matter described below:
    Client machine has been setup with MS Outlook 2016 on MS Windows 7 SP1.
    Exactly the same installation of MS Outlook 2016 made on MS Windows 10 Enterprise LTSC.
    Weird Results:
    Machine running Outlook 2016 under Windows 7 cannot access Z-Push server newer than v2.4.5 neither server running original MS ActiveSync 14.1 .
    Machine that using Windows 10/Outlook 2016 can connect to both servers Z-Push 2.5.x/ActiveSync 14.1 with no issues at all.
    Servers log are blank while connecting with Outlook 2016 on Windows 7.
    So, looks like is OS-specific problem.
    My question actually: @Manfred, do you ever know, if Microsoft has broken backward compatibility between MS ActiveSync releases? And this means that client’s ActiveSync implementation has partially hard-coded in some OS dependant libs?
    IMHO, that’s the strangest issue I ran into this year :-)

  • Here are results of test from “original” implementation server with Zextras MobileSync running Active Sync 14.1
    As you can see, there is 449 response code Retry With, which means client provides insufficient information. From my side I guess that information is insufficient for the FolderSync EAS command, does it correct?

  • I managed to solve the problem on my own.
    We must enable TLS1.1, TLS1.2 support for WinHTTP libraries in Windows 7 to get all stuff up and running.
    The End :-)

    IMHO, it might be applicable to newer Z-Push version too, but I can’t test it on my side at the moment.

  • @Finji Correct. Otherwise you have to enable TLS 1.0 on your Autodiscover site. This is documented by Microsoft and there is a Microsoft FixIt to set Windows 7 up correctly.

    You would have the same problem with newer Z-Push versions as well.

    This ONLY affects AutoDiscover. IMAP/SMTP and CalDav backends can run TLS 1.1, 1.2, or 1.3 AS SUPPORTED by the client’s standard stack and that web server.