diff --git a/NEWS b/NEWS
index a8965419a..8b396584d 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,7 @@ master
 ------
 
 Enhancements
+ - Sharing request among different Outlook versions
  - Improve sync speed from Outlook by non-reprocessing already downloaded unread mails
 
 Bug fixes
diff --git a/OpenChange/MAPIStoreMailFolder.h b/OpenChange/MAPIStoreMailFolder.h
index 2263f955b..c56e74862 100644
--- a/OpenChange/MAPIStoreMailFolder.h
+++ b/OpenChange/MAPIStoreMailFolder.h
@@ -55,6 +55,11 @@
 - (NSData *) changeKeyForMessageWithKey: (NSString *) messageKey;
 - (NSData *) predecessorChangeListForMessageWithKey: (NSString *) messageKey;
 
+/* Extra properties from mail messages that already hit the server */
+- (void) setExtraProperties: (NSDictionary *) props
+                 forMessage: (NSString *) messageKey;
+- (NSDictionary *) extraPropertiesForMessage: (NSString *) messageKey;
+
 @end
 
 /* MAPIStoreOutboxFolder is a special subclass of MAPIStoreMailFolder where
diff --git a/OpenChange/MAPIStoreMailFolder.m b/OpenChange/MAPIStoreMailFolder.m
index ba2339586..f0a6c33bc 100644
--- a/OpenChange/MAPIStoreMailFolder.m
+++ b/OpenChange/MAPIStoreMailFolder.m
@@ -964,6 +964,37 @@ _compareFetchResultsByMODSEQ (id entry1, id entry2, void *data)
   return list;
 }
 
+/* Management for extra properties once they already hit the IMAP server */
+- (void) setExtraProperties: (NSDictionary *) props
+                 forMessage: (NSString *) messageKey
+{
+  NSMutableDictionary *extraProps, *currentProperties;
+  NSString *messageUid;
+
+  messageUid = [self messageUIDFromMessageKey: messageKey];
+  currentProperties = [versionsMessage properties];
+  extraProps = [currentProperties objectForKey: @"ExtraMessagesProperties"];
+  if (!extraProps)
+    {
+      extraProps = [NSMutableDictionary new];
+      [currentProperties setObject: extraProps forKey: @"ExtraMessagesProperties"];
+      [extraProps release];
+    }
+
+  [extraProps setObject: props
+                 forKey: messageUid];
+  [versionsMessage save];
+}
+
+- (NSDictionary *) extraPropertiesForMessage: (NSString *) messageKey
+{
+  NSString *messageUid;
+
+  messageUid = [self messageUIDFromMessageKey: messageKey];
+  return [[[versionsMessage properties] objectForKey: @"ExtraMessagesProperties"]
+                   objectForKey: messageUid];
+}
+
 - (NSArray *) getDeletedKeysFromChangeNumber: (uint64_t) changeNum
                                        andCN: (NSNumber **) cnNbr
                                  inTableType: (uint8_t) tableType
diff --git a/OpenChange/MAPIStoreMailMessage.m b/OpenChange/MAPIStoreMailMessage.m
index 8c35f4265..c0ca8f9b6 100644
--- a/OpenChange/MAPIStoreMailMessage.m
+++ b/OpenChange/MAPIStoreMailMessage.m
@@ -65,7 +65,7 @@
 
 @class iCalCalendar, iCalEvent;
 
-static Class NSExceptionK;
+static Class NSExceptionK, MAPIStoreSharingMessageK;
 
 @interface NSString (MAPIStoreMIME)
 
@@ -108,6 +108,7 @@ static Class NSExceptionK;
 + (void) initialize
 {
   NSExceptionK = [NSException class];
+  MAPIStoreSharingMessageK = [MAPIStoreSharingMessage class];
 }
 
 - (id) init
@@ -267,7 +268,8 @@ _compareBodyKeysByPriority (id entry1, id entry2, void *data)
                  a sharing object is a proxy in a mail message */
               sharingMessage = [[MAPIStoreSharingMessage alloc]
                                  initWithMailHeaders: [sogoObject mailHeaders]
-                                   andConnectionInfo: [[self context] connectionInfo]];
+                                   andConnectionInfo: [[self context] connectionInfo]
+                                         fromMessage: self];
               [self addProxy: sharingMessage];
               [sharingMessage release];
             }
@@ -1641,6 +1643,21 @@ _compareBodyKeysByPriority (id entry1, id entry2, void *data)
   bodySetup = YES;
 }
 
+- (MAPIStoreSharingMessage *) _sharingObject
+{
+  /* Get the sharing object if available */
+  NSUInteger i, max;
+  id proxy;
+
+  max = [proxies count];
+  for (i = 0; i < max; i++) {
+    proxy = [proxies objectAtIndex: i];
+    if ([proxy isKindOfClass: MAPIStoreSharingMessageK])
+      return proxy;
+  }
+  return nil;
+}
+
 - (void) save: (TALLOC_CTX *) memCtx 
 {
   NSNumber *value;
@@ -1654,6 +1671,11 @@ _compareBodyKeysByPriority (id entry1, id entry2, void *data)
       else /* 0: unflagged, 1: follow up complete */
         [sogoObject removeFlags: @"\\Flagged"];
     }
+
+  if (mailIsSharingObject)
+    [[self _sharingObject] saveWithMessage: self
+                             andSOGoObject: sogoObject];
+
 }
 
 @end
diff --git a/OpenChange/MAPIStoreMailVolatileMessage.m b/OpenChange/MAPIStoreMailVolatileMessage.m
index 77d6294ab..b5239f193 100644
--- a/OpenChange/MAPIStoreMailVolatileMessage.m
+++ b/OpenChange/MAPIStoreMailVolatileMessage.m
@@ -28,6 +28,7 @@
 #import <Foundation/NSArray.h>
 #import <Foundation/NSData.h>
 #import <Foundation/NSDictionary.h>
+#import <Foundation/NSScanner.h>
 #import <Foundation/NSString.h>
 #import <Foundation/NSValue.h>
 #import <NGExtensions/NGBase64Coding.h>
@@ -541,6 +542,7 @@ FillMessageHeadersFromSharingProperties (NGMutableHashMap *headers, NSDictionary
      about the properties */
 
   id value;
+  NSNumber *sharingFlavourNum = nil;
 
   value = [mailProperties objectForKey: MAPIPropertyKey (PidLidSharingCapabilities)];
   if (value)
@@ -549,8 +551,32 @@ FillMessageHeadersFromSharingProperties (NGMutableHashMap *headers, NSDictionary
 
   value = [mailProperties objectForKey: MAPIPropertyKey (PidLidSharingFlavor)];
   if (value)
-    [headers setObject: value
-                forKey: @"X-MS-Sharing-Flavor"];
+    sharingFlavourNum = (NSNumber *)value;
+  else
+    {
+      value = [mailProperties objectForKey: MAPIPropertyKey (PidNameXSharingFlavor)];
+      if (value)
+        {
+          /* Transform the hex string to unsigned int */
+          NSScanner *scanner;
+          unsigned int sharingFlavour;
+          scanner = [NSScanner scannerWithString:value];
+          if ([scanner scanHexInt:&sharingFlavour])
+            sharingFlavourNum =[NSNumber numberWithUnsignedInt: sharingFlavour];
+        }
+    }
+  if (sharingFlavourNum)
+    {
+      if ([sharingFlavourNum unsignedIntegerValue] == 0x5100)
+        {
+          /* 0x5100 sharing flavour is not in standard but it seems to
+             be a denial of request + invitation message so we store
+             deny sharing flavour */
+          sharingFlavourNum = [NSNumber numberWithUnsignedInt: SHARING_DENY_REQUEST];
+        }
+      [headers setObject: sharingFlavourNum
+                  forKey: @"X-MS-Sharing-Flavor"];
+    }
 
   value = [mailProperties objectForKey: MAPIPropertyKey (PidLidSharingInitiatorEntryId)];
   if (value)
diff --git a/OpenChange/MAPIStoreSharingMessage.h b/OpenChange/MAPIStoreSharingMessage.h
index 9b62389a0..7db7f552f 100644
--- a/OpenChange/MAPIStoreSharingMessage.h
+++ b/OpenChange/MAPIStoreSharingMessage.h
@@ -23,8 +23,10 @@
 #ifndef MAPISTORESHARINGMESSAGE_H
 #define MAPISTORESHARINGMESSAGE_H
 
+#import "MAPIStoreMailMessage.h"
 #import "MAPIStoreObjectProxy.h"
 
+#define SHARING_SPECIAL_FOLDER 0x40290
 
 @interface MAPIStoreSharingMessage : MAPIStoreObjectProxy
 {
@@ -33,7 +35,8 @@
 }
 
 - (id) initWithMailHeaders: (NSDictionary *) mailHeaders
-         andConnectionInfo: (struct mapistore_connection_info *) newConnInfo;
+         andConnectionInfo: (struct mapistore_connection_info *) newConnInfo
+               fromMessage: (MAPIStoreMailMessage *) msg;
 
 /* getters */
 - (int) getPidLidSharingCapabilities: (void **) data
@@ -89,6 +92,10 @@
 - (int) getPidNameContentClass: (void **) data
                       inMemCtx: (TALLOC_CTX *) memCtx;
 
+/* Save */
+- (void) saveWithMessage: (MAPIStoreMailMessage *) msg
+           andSOGoObject: (SOGoMailObject *) sogoObject;
+
 @end
 
 #endif /* MAPISTORECALENDARWRAPPER_H */
diff --git a/OpenChange/MAPIStoreSharingMessage.m b/OpenChange/MAPIStoreSharingMessage.m
index 594863e0e..ba0c74132 100644
--- a/OpenChange/MAPIStoreSharingMessage.m
+++ b/OpenChange/MAPIStoreSharingMessage.m
@@ -22,9 +22,11 @@
 
 #include <talloc.h>
 
+#import <Foundation/NSArray.h>
 #import <Foundation/NSData.h>
 #import <Foundation/NSDictionary.h>
 
+#import <Mailer/SOGoMailObject.h>
 #import <NGExtensions/NGBase64Coding.h>
 
 #import "MAPIStoreTypes.h"
@@ -33,9 +35,12 @@
 #import "NSString+MAPIStore.h"
 #import "NSValue+MAPIStore.h"
 
+#import "MAPIStoreMailFolder.h"
 #import "MAPIStoreSharingMessage.h"
 
+#include <mapistore/mapistore.h>
 #include <mapistore/mapistore_errors.h>
+#include <mapistore/mapistore_nameid.h>
 
 @implementation MAPIStoreSharingMessage
 
@@ -52,6 +57,7 @@
 
 - (id) initWithMailHeaders: (NSDictionary *) mailHeaders
          andConnectionInfo: (struct mapistore_connection_info *) newConnInfo
+               fromMessage: (MAPIStoreMailMessage *) msg
 {
   NSEnumerator *enumerator;
   NSString *key;
@@ -67,6 +73,12 @@
             [properties setObject: [mailHeaders objectForKey: key]
                            forKey: key];
         }
+
+      /* Set request properties from container folder */
+      NSDictionary *requestProps = [(MAPIStoreMailFolder *)[msg container]
+                                       extraPropertiesForMessage: [msg nameInContainer]];
+      if (requestProps)
+        [properties addEntriesFromDictionary: requestProps];
     }
 
   return self;
@@ -123,7 +135,8 @@
   value = [properties objectForKey: @"x-ms-sharing-capabilities"];
   if (value)
     {
-      *data = [[value stringValue] asUnicodeInMemCtx: memCtx];
+      *data = [[NSString stringWithFormat:@"%X", [value intValue]]
+                 asUnicodeInMemCtx: memCtx];
       rc = MAPISTORE_SUCCESS;
     }
 
@@ -163,28 +176,28 @@
       value = [properties objectForKey: @"x-ms-sharing-capabilities"];
       if (value)
         {
-          if ([value intValue] == 0x40290)  /* Special folder */
+          if ([value intValue] == SHARING_SPECIAL_FOLDER)
             {
               value = [properties objectForKey: @"x-ms-sharing-responsetime"];
-              auxValue = [properties objectForKey: @"x-ms-sharing-remotename"];
+              auxValue = [properties objectForKey: @"x-ms-sharing-remoteuid"];
               if (value)  /* A sharing request */
                 {
                   if (auxValue)
-                    *data = MAPILongValue (memCtx, 0x20710);
+                    *data = MAPILongValue (memCtx, SHARING_INVITATION_REQUEST_FOLDER);
                   else
-                    *data = MAPILongValue (memCtx, 0x20500);
+                    *data = MAPILongValue (memCtx, SHARING_REQUEST_SPECIAL_FOLDER);
                 }
               else
                 {
-                  if (auxValue)  /* It SHOULD be an invitation or response acceptance */
-                    *data = MAPILongValue (memCtx, 0x20310);
-                  else
-                    *data = MAPILongValue (memCtx, 0x23310);
+                  if (auxValue)  /* It SHOULD be an invitation or response */
+                    *data = MAPILongValue (memCtx, SHARING_INVITATION_SPECIAL_FOLDER);
+                  else  /* No remote info, then denial */
+                    *data = MAPILongValue (memCtx, SHARING_DENY_REQUEST);
                 }
             }
           else
             {
-              *data = MAPILongValue (memCtx, 0x310);
+              *data = MAPILongValue (memCtx, SHARING_INVITATION_FOLDER);
             }
           rc = MAPISTORE_SUCCESS;
         }
@@ -202,7 +215,8 @@
   value = [properties objectForKey: @"x-ms-sharing-flavor"];
   if (value)
     {
-      *data = [[value stringValue] asUnicodeInMemCtx: memCtx];
+      *data = [[NSString stringWithFormat:@"%X", [value intValue]]
+                asUnicodeInMemCtx: memCtx];
       rc = MAPISTORE_SUCCESS;
     }
 
@@ -368,7 +382,18 @@
   enum mapistore_error rc = MAPISTORE_ERR_NOT_FOUND;
   id value;
 
-  value = [properties objectForKey: @"x-ms-sharing-responsetime"];
+  value = [properties objectForKey: MAPIPropertyKey (PidLidSharingResponseTime)];
+  if (!value)
+    {
+      value = [properties objectForKey: @"x-ms-sharing-responsetime"];
+      if (value)
+        {
+          /* Here the value is a GSCBufferString */
+          NSString * responseTime = [NSString stringWithUTF8String: [value UTF8String]];
+          value = [NSDate dateWithString: responseTime];
+        }
+    }
+
   if (value)
     {
       *data = [value asFileTimeInMemCtx: memCtx];
@@ -385,7 +410,10 @@
   enum mapistore_error rc = MAPISTORE_ERR_NOT_FOUND;
   id value;
 
-  value = [properties objectForKey: @"x-ms-sharing-responsetype"];
+  value = [properties objectForKey: MAPIPropertyKey (PidLidSharingResponseType)];
+  if (!value)
+    value = [properties objectForKey: @"x-ms-sharing-responsetype"];
+
   if (value)
     {
       *data = MAPILongValue (memCtx, [value intValue]);
@@ -398,8 +426,38 @@
 - (int) getPidNameContentClass: (void **) data
                       inMemCtx: (TALLOC_CTX *) memCtx
 {
-    *data = talloc_strdup (memCtx, "Sharing");
-    return MAPISTORE_SUCCESS;
+  *data = talloc_strdup (memCtx, "Sharing");
+  return MAPISTORE_SUCCESS;
+}
+
+- (void) saveWithMessage: (MAPIStoreMailMessage *) msg
+           andSOGoObject: (SOGoMailObject *) sogoObject
+{
+  /* Store PidLidSharingResponseType and PidLidSharingResponseTime if
+     required in versions message from the container as I don't see
+     other straightforward place to put that information */
+  id response;
+  NSDictionary *propsToStore;
+
+  response = [[msg properties] objectForKey: MAPIPropertyKey (PidLidSharingResponseType)];
+  if (response)
+    {
+      /* FIXME: Is there any better way to increase the modseq? */
+      [sogoObject addFlags: @"\\Draft"];
+      [sogoObject removeFlags: @"\\Draft"];
+
+      /* Store this modification in container folder along the property values */
+      propsToStore = [NSDictionary dictionaryWithObjects:
+                               [NSArray arrayWithObjects: response,
+                                        [[msg properties] objectForKey: MAPIPropertyKey (PidLidSharingResponseTime)],
+                                        nil]
+                                                 forKeys:
+                               [NSArray arrayWithObjects: MAPIPropertyKey (PidLidSharingResponseType),
+                                        MAPIPropertyKey (PidLidSharingResponseTime), nil]];
+
+      [(MAPIStoreMailFolder *)[msg container] setExtraProperties: propsToStore
+                                                      forMessage: [msg nameInContainer]];
+    }
 }
 
 @end