diff --git a/ChangeLog b/ChangeLog
index cd8723c63..448a73e93 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 2011-09-27  Wolfgang Sourdeau  <wsourdeau@inverse.ca>
 
+	* OpenChange/MAPIStoreFolder.m
+	(-moveCopyMessagesWithMID:fromFolder:withMID:wantCopy:): ensure
+	the message URL exists in the MAPIStoreMapping, otherwise fail
+	with MAPISTORE_ERR_NOT_FOUND, to avoid a crash.
+
 	* OpenChange/MAPIStoreFSMessage.m (-objectVersion): return
 	0xff...fff when "version" does not exist in the object properties.
 
diff --git a/OpenChange/MAPIStoreFolder.m b/OpenChange/MAPIStoreFolder.m
index 3e60e4ee4..e758d3eb6 100644
--- a/OpenChange/MAPIStoreFolder.m
+++ b/OpenChange/MAPIStoreFolder.m
@@ -641,6 +641,7 @@ Class NSExceptionK, MAPIStoreFAIMessageK, MAPIStoreMessageTableK, MAPIStoreFAIMe
   int rc = MAPISTORE_SUCCESS;
   NSUInteger count;
   NSMutableArray *oldMessageURLs;
+  NSString *oldMessageURL;
   MAPIStoreMapping *mapping;
 
   if ([sourceFolder isKindOfClass: isa]
@@ -651,11 +652,17 @@ Class NSExceptionK, MAPIStoreFAIMessageK, MAPIStoreMessageTableK, MAPIStoreFAIMe
   mapping = [[self context] mapping];
   for (count = 0; rc == MAPISTORE_SUCCESS && count < midCount; count++)
     {
-      [oldMessageURLs addObject: [mapping urlFromID: srcMids[count]]];
-      rc = [self moveCopyMessageWithMID: srcMids[count]
-                             fromFolder: sourceFolder
-                                withMID: targetMids[count]
-                               wantCopy: wantCopy];
+      oldMessageURL = [mapping urlFromID: srcMids[count]];
+      if (oldMessageURL)
+        {
+          [oldMessageURLs addObject: oldMessageURL];
+          rc = [self moveCopyMessageWithMID: srcMids[count]
+                                 fromFolder: sourceFolder
+                                    withMID: targetMids[count]
+                                   wantCopy: wantCopy];
+        }
+      else
+        rc = MAPISTORE_ERR_NOT_FOUND;
     }
 
   /* Notifications */