diff --git a/ActiveSync/SOGoActiveSyncDispatcher+Sync.m b/ActiveSync/SOGoActiveSyncDispatcher+Sync.m
index b214984d1..54d827453 100644
--- a/ActiveSync/SOGoActiveSyncDispatcher+Sync.m
+++ b/ActiveSync/SOGoActiveSyncDispatcher+Sync.m
@@ -64,6 +64,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #import <EOControl/EOQualifier.h>
 
 #import <SOGo/NSArray+DAV.h>
+#import <SOGo/SOGoCache.h>
 #import <SOGo/NSDictionary+DAV.h>
 #import <SOGo/SOGoDAVAuthenticator.h>
 #import <SOGo/SOGoDomainDefaults.h>
@@ -567,8 +568,8 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     default:
       {
         NSMutableArray *addedOrChangedMessages;
+        NSString *uid, *command, *key;
         SOGoMailObject *mailObject;
-        NSString *uid, *command;
         NSDictionary *aMessage;
         NSArray *allMessages;
         int deleted_count;
@@ -618,6 +619,20 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
             uid = [[[aMessage allKeys] lastObject] stringValue];
             command = [[aMessage allValues] lastObject];          
             
+            // We check for Outlook stupidity to avoid creating duplicates - see the comment
+            // in SOGoActiveSyncDispatcher.m: -processMoveItems:inResponse: for more details.
+            key = [NSString stringWithFormat: @"%@+%@+%@+%@",
+                            [[context activeUser] login],
+                       [context objectForKey: @"DeviceType"],
+                            [theCollection displayName],
+                            uid];
+            
+            if ([[SOGoCache sharedCache] valueForKey: key])
+              {
+                [[SOGoCache sharedCache] removeValueForKey: key];
+                command = @"changed";
+              }
+            
             if ([command isEqualToString: @"added"])
               [s appendString: @"<Add xmlns=\"AirSync:\">"];
             else
diff --git a/ActiveSync/SOGoActiveSyncDispatcher.m b/ActiveSync/SOGoActiveSyncDispatcher.m
index 5a64cf6c8..1143219fd 100644
--- a/ActiveSync/SOGoActiveSyncDispatcher.m
+++ b/ActiveSync/SOGoActiveSyncDispatcher.m
@@ -76,6 +76,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #import <SOGo/NSArray+DAV.h>
 #import <SOGo/NSDictionary+DAV.h>
+#import <SOGo/SOGoCache.h>
 #import <SOGo/SOGoDAVAuthenticator.h>
 #import <SOGo/SOGoDomainDefaults.h>
 #import <SOGo/SOGoMailer.h>
@@ -880,10 +881,6 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
       NSDictionary *response;
       NSString *v;
-
-      // userFolder = [[context activeUser] homeFolderInContext: context];
-      // accountsFolder = [userFolder lookupName: @"Mail"  inContext: context  acquire: NO];
-      // currentFolder = [accountsFolder lookupName: @"0"  inContext: context  acquire: NO];
       
       currentCollection = [self collectionFromId: srcFolderId  type: srcFolderType];
 
@@ -925,6 +922,28 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
           NSMutableString *s;
           NSData *d;
           
+          //
+          // If the MoveItems operation is initiated by an Outlook client, we save the "deviceType+dstMessageId" to use it later in order to
+          // modify the Sync command from "add" to "change" (see SOGoActiveSyncDispatcher+Sync.m: -processSyncGetChanges: ...).
+          // This is to avoid Outlook creating dupes when moving messages across folfers.
+          //
+          if ([[context objectForKey: @"DeviceType"] isEqualToString: @"WindowsOutlook15"])
+            {
+              NSString *key;
+
+              // The key must be pretty verbose. We use the <uid>+<DeviceType>+<target folder>+<DstMsgId>
+              key = [NSString stringWithFormat: @"%@+%@+%@+%@",
+                              [[context activeUser] login],
+                              [context objectForKey: @"DeviceType"],
+                              dstFolderId,
+                              dstMessageId];
+                              
+
+              [[SOGoCache sharedCache] setValue: @"MovedItem"
+                                         forKey: key];
+            }
+
+          
           // Everything is alright, lets return the proper response. "Status == 3" means success.
           s = [NSMutableString string];
           
@@ -1522,9 +1541,10 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
   ASSIGN(context, theContext);
  
-  // Get the device ID and "stash" it
+  // Get the device ID, device type and "stash" them
   deviceId = [[theRequest uri] deviceId];
   [context setObject: deviceId  forKey: @"DeviceId"];
+  [context setObject: [[theRequest uri] deviceType]  forKey: @"DeviceType"];
 
   d = [[theRequest content] wbxml2xml];
   documentElement = nil;