[[toc]] + Known broken !ActiveSync client behavior Many clients do not follow the published ActiveSync protocol specification. In fact, even some of Microsoft's products are guilty of this. Horde_ActiveSync attempts to work around those issues that are possible to do so. This page attempts to document some of these idiosyncrasies that we are not (yet?) able to workaround. Some broken behavior seems to be wide spread, and are documented in the //General// section. More specific behavior is documented in client specific sections. ++ General +++ The sending of STATUS_FOLDERSYNC_REQUIRED (12) is ignored by a large number of clients. This status code is issued in response to a SYNC request when the server is unable to locate the folder data in the hierarchy cache. I.e., the folder looks to no longer exist. This can happen when something causes the server stored state to disappear (like when explicitly removing a device from the server) or when something corrupts the stored data. This is supposed to trigger the client to issue a FOLDERSYNC request to freshen the hierarchy cache. Some clients will continue to issue the exact same SYNC request in response to this status code, causing a sync loop. Other clients will accurately issue the FOLDERSYNC request, but fail to update their local cache. Outlook 2013 does this. On receiving new FOLDERSYNC responses, it continues to issue SYNC requests on the old folderids (though it DOES reset the synckey, so **something** is happening in the client, just not the correct something). Typically, the only way to resolve this issue is to remove the account from the client and recreate it from scratch. ++ Outlook 2013 +++ Duplicate email items due to broken MOVEITEMS request handling.##red|(Worked around as of Horde_ActiveSync 2.16.3)## When moving email items from one folder to another, or deleting them, Outlook does not follow the specification for handling the move, which leads to duplicate email items being present in the destination folder. There are two issues interacting here that cause this. The first, is that Outlook moves the local item on its own, without waiting for the DELETE and ADD commands to be issued from the server. Instead, it reassigns the existing email the new UID received in the MOVEITEMS response. Secondly, when it receives the ADD command for the new email in the destination folder, it fails to treat this command as an UPDATE command as the specification says you must when an ADD command is received for an already existing UID. ++ Android 4.4 !KitKat +++ Broken attachment handling. Android versions 4.4.0 through 4.4.2 have many issues regarding email synchronization. The largest of which is the inability to download attachments. Attempting to do so normally results in force closing of the Email application. This issue cannot be worked around in code, but is fixed in Android 4.4.3.