diff --git a/OpenChange/MAPIStoreFolder.m b/OpenChange/MAPIStoreFolder.m
index 0d862b85e..824c15578 100644
--- a/OpenChange/MAPIStoreFolder.m
+++ b/OpenChange/MAPIStoreFolder.m
@@ -402,7 +402,8 @@ Class NSExceptionK, MAPIStoreFAIMessageK, MAPIStoreMessageTableK, MAPIStoreFAIMe
              withRow: (struct SRow *) aRow
               andFID: (uint64_t) fid
 {
-  int rc = MAPISTORE_SUCCESS;
+  BOOL mapped;
+  enum mapistore_error rc = MAPISTORE_SUCCESS;
   MAPIStoreMapping *mapping;
   NSString *baseURL, *childURL, *folderKey;
   MAPIStoreFolder *childFolder;
@@ -430,7 +431,12 @@ Class NSExceptionK, MAPIStoreFAIMessageK, MAPIStoreMessageTableK, MAPIStoreFAIMe
               childURL = [NSString stringWithFormat: @"%@%@/",
                                    baseURL,
                                    [folderKey stringByAddingPercentEscapesUsingEncoding: NSUTF8StringEncoding]];
-              [mapping registerURL: childURL withID: fid];
+
+              mapped = [mapping registerURL: childURL withID: fid];
+              if (!mapped)
+                /* Enforce the creation if the backend does know the fid */
+                [mapping updateURL: childURL withID: fid];
+
               childFolder = [self lookupFolder: folderKey];
               if (childFolder)
                 {
diff --git a/OpenChange/MAPIStoreMapping.h b/OpenChange/MAPIStoreMapping.h
index 827cddf38..55c2e944a 100644
--- a/OpenChange/MAPIStoreMapping.h
+++ b/OpenChange/MAPIStoreMapping.h
@@ -60,6 +60,8 @@
                     andFlags: (uint8_t) flags;
 - (void) updateID: (uint64_t) idNbr
           withURL: (NSString *) urlString;
+- (BOOL) updateURL: (NSString *) urlString
+            withID: (uint64_t) idNbr;
 
 @end
 
diff --git a/OpenChange/MAPIStoreMapping.m b/OpenChange/MAPIStoreMapping.m
index 6a910ea4c..b7d303ed6 100644
--- a/OpenChange/MAPIStoreMapping.m
+++ b/OpenChange/MAPIStoreMapping.m
@@ -227,12 +227,32 @@ MAPIStoreMappingKeyFromId (uint64_t idNbr)
     }
 }
 
+- (BOOL) updateURL: (NSString *) urlString
+            withID: (uint64_t) idNbr
+{
+  BOOL rc = NO;
+  uint64_t oldIDNbr;
+
+  oldIDNbr = [self idFromURL: urlString];
+  if (oldIDNbr)
+    {
+      [self logWithFormat: @"Updating URL: %@ with id %.16"PRIx64" from old id %.16"PRIx64,
+            urlString, idNbr, oldIDNbr];
+      [self unregisterURLWithID: oldIDNbr];
+      [self registerURL: urlString
+                 withID: idNbr];
+      rc = YES;
+    }
+
+  return rc;
+}
+
 - (BOOL) registerURL: (NSString *) urlString
               withID: (uint64_t) idNbr
 {
   NSString *oldURL;
   uint64_t oldIdNbr;
-  bool rc, softDeleted;
+  bool softDeleted;
 
   oldURL = [self urlFromID: idNbr];
   if (oldURL != NULL)
@@ -257,7 +277,6 @@ MAPIStoreMappingKeyFromId (uint64_t idNbr)
     }
   else
     {
-      rc = YES;
       // [self logWithFormat: @"registered url '%@' with id %lld (0x%.16"PRIx64")",
       //       urlString, idNbr, idNbr];
 
@@ -266,7 +285,7 @@ MAPIStoreMappingKeyFromId (uint64_t idNbr)
                          idNbr, [urlString UTF8String]);
     }
 
-  return rc;
+  return YES;
 }
 
 - (void) registerURLs: (NSArray *) urlStrings