How Microsoft is trying to send mobile mail to itself

    Does Outlook-iOS-Android store a copy of the mailbox on the Microsoft server?

    Many corporate users who recently upgraded to iOS 11 found themselves in limbo. The fact is that after the upgrade the standard client ( with resources on Exchange Server 2016, Office 365 or stops working.

    Sending message ends with the error “Cannot Send Mail The message was rejected by the server. ”

    The problem is that Exchange 2016 uses HTTPS / 2 TLS connections for its clients. When an iOS mail application tries to connect to Exchange using ActiveSync, it incorrectly negotiates the connection.

    Microsoft has confirmed the problem and as a solution proposes to install the Outlook for iOS client .

    This decision is very controversial, because Outlook does not connect directly to the mail server, and with the entered accounts, a Microsoft server located in the USA connects to your server and most likely downloads a copy of your mailbox to it.

    Below is a fragment of the analysis of connection logs from SkypeTime .

    In the Russian segment, this issue has not been given sufficient attention, therefore, we provide links to foreign sources.


    As far as it is legally correct and good, we will not judge, but to increase the level of confidentiality, you can block the connection from these servers to Exchange 2016.

    New-ActiveSyncDeviceAccessRule -QueryString "Outlook for iOS and Android" -Characteristic DeviceModel -AccessLevel Block

    I hope this information will be useful to someone.
    Sincerely, the team of the company

    Also popular now: