diff --git a/arch/x86/scc/Makefile b/arch/x86/scc/Makefile
index 2003a259..c3ffb3c8 100644
--- a/arch/x86/scc/Makefile
+++ b/arch/x86/scc/Makefile
@@ -1,4 +1,4 @@
-C_source := icc.c SCC_API.c iRCCE_admin.c iRCCE_send.c iRCCE_isend.c iRCCE_irecv.c iRCCE_recv.c iRCCE_get.c iRCCE_put.c iRCCE_synch.c RCCE_malloc.c RCCE_shmalloc.c RCCE_debug.c RCCE_qsort.c RCCE_DCMflush.c RCCE_send.c RCCE_recv.c RCCE_flags.c RCCE_comm.c RCCE_put.c RCCE_get.c RCCE_synch.c RCCE_bcast.c RCCE_admin.c # RCCE_power_management.c
+C_source := icc.c SCC_API.c iRCCE_admin.c iRCCE_mailbox.c iRCCE_send.c iRCCE_isend.c iRCCE_irecv.c iRCCE_recv.c iRCCE_get.c iRCCE_put.c iRCCE_synch.c RCCE_malloc.c RCCE_shmalloc.c RCCE_debug.c RCCE_qsort.c RCCE_DCMflush.c RCCE_send.c RCCE_recv.c RCCE_flags.c RCCE_comm.c RCCE_put.c RCCE_get.c RCCE_synch.c RCCE_bcast.c RCCE_admin.c # RCCE_power_management.c
 ASM_source := 
 MODULE := arch_x86_scc
 
diff --git a/arch/x86/scc/iRCCE_admin.c b/arch/x86/scc/iRCCE_admin.c
index c61d66b9..ba465765 100644
--- a/arch/x86/scc/iRCCE_admin.c
+++ b/arch/x86/scc/iRCCE_admin.c
@@ -47,6 +47,27 @@ iRCCE_SEND_REQUEST* iRCCE_isend_queue;
 // recv request queue
 iRCCE_RECV_REQUEST* iRCCE_irecv_queue[RCCE_MAXNP];
 
+// recv request queue for those with source = iRCCE_ANY_SOURCE:
+iRCCE_RECV_REQUEST* iRCCE_irecv_any_source_queue;
+
+// mailbox in MPB
+volatile iRCCE_MAIL_HEADER* iRCCE_mailbox_recv[RCCE_MAXNP]; // store addresses for receiving headers
+volatile iRCCE_MAIL_HEADER* iRCCE_mailbox_send[RCCE_MAXNP]; // store addresses for sending headeres
+
+// mailbox recv queue
+iRCCE_MAIL_HEADER* iRCCE_mailbox_recv_queue[iRCCE_PRIOS];
+
+// mail garbage queue
+iRCCE_MAIL_TRASH_BIN iRCCE_mail_garbage;
+
+// flag indicating if last header was received
+iRCCE_SHORT_FLAG iRCCE_last_mail[RCCE_MAXNP]; 
+
+// field to store open/closed status of mailboxes
+iRCCE_SHORT_FLAG iRCCE_mailbox_status[RCCE_MAXNP];
+
+
+
 //--------------------------------------------------------------------------------------
 // FUNCTION: iRCCE_init
 //--------------------------------------------------------------------------------------
@@ -56,10 +77,34 @@ int iRCCE_init(void) {
   int i;
 
   for(i=0; i<RCCE_MAXNP; i++) {
-    iRCCE_irecv_queue[i] = NULL;
+    iRCCE_irecv_queue[i] 	= NULL;
+    iRCCE_mailbox_recv[i] 	= NULL;
+    iRCCE_mailbox_send[i]	= NULL;
+    iRCCE_last_mail[i] 		= 0;
+    iRCCE_mailbox_status[i]	= iRCCE_MAILBOX_OPEN;
   }
 
   iRCCE_isend_queue = NULL;
+  iRCCE_irecv_any_source_queue = NULL;
+
+  // init trash bin for mailbox
+  iRCCE_mail_garbage.first = NULL;
+  iRCCE_mail_garbage.last  = NULL;
+
+  // init mail-priority lists  
+  for( i=0; i<iRCCE_PRIOS; ++i ) {
+	  iRCCE_mailbox_recv_queue[i] = NULL;
+  }
+  // allocate space in MPB for mailbox and set senders mailbox-pointer
+  for( i=0; i<RCCE_NP; i++ ) {
+   iRCCE_mailbox_recv[i] = (iRCCE_MAIL_HEADER*)RCCE_malloc(RCCE_LINE_SIZE); 
+  
+  }
+
+ 
+  for( i=0; i<RCCE_NP; i++ ) {
+    iRCCE_mailbox_send[i] = (iRCCE_MAIL_HEADER*)(RCCE_comm_buffer[i] + ((RCCE_buff_ptr - RCCE_comm_buffer[RCCE_IAM]) - (RCCE_NP-RCCE_IAM)*RCCE_LINE_SIZE ));
+  }
 
   return (iRCCE_SUCCESS);
 }
diff --git a/arch/x86/scc/iRCCE_isend.c b/arch/x86/scc/iRCCE_isend.c
index 18c9dca0..15c4e242 100644
--- a/arch/x86/scc/iRCCE_isend.c
+++ b/arch/x86/scc/iRCCE_isend.c
@@ -1,12 +1,12 @@
-//***************************************************************************************
+//******************************************************************************
 // Non-blocking send routines. 
-//***************************************************************************************
+//******************************************************************************
 //
 // Author: Rob F. Van der Wijngaart
 //         Intel Corporation
 // Date:   008/30/2010
 //
-//***************************************************************************************
+//******************************************************************************
 // 
 // Copyright 2010 Intel Corporation
 // 
@@ -158,56 +158,115 @@ static void iRCCE_init_send_request(
 }
 
 //--------------------------------------------------------------------------------------
-// FUNCTION: iRCCE_isend
+// FUNCTION: iRCCE_isend_general
 //--------------------------------------------------------------------------------------
 // non-blocking send function; returns a handle of type iRCCE_SEND_REQUEST
 //--------------------------------------------------------------------------------------
 static iRCCE_SEND_REQUEST blocking_isend_request;
-int iRCCE_isend(char *privbuf, size_t size, int dest, iRCCE_SEND_REQUEST *request) {
+static int iRCCE_isend_general(char *privbuf, size_t size, int dest, iRCCE_SEND_REQUEST *request) {
 
-	if(request == NULL) request = &blocking_isend_request;
 
-	if (dest<0 || dest >= RCCE_NP) 
-		return(RCCE_error_return(RCCE_debug_comm,RCCE_ERROR_ID));
-	else {
-		iRCCE_init_send_request(privbuf, RCCE_buff_ptr, RCCE_chunk, 
-				&RCCE_ready_flag[dest], &RCCE_sent_flag[RCCE_IAM], 
-				size, dest, request);
 
-		if(iRCCE_isend_queue == NULL) {
+	iRCCE_init_send_request(privbuf, RCCE_buff_ptr, RCCE_chunk, 
+			&RCCE_ready_flag[dest], &RCCE_sent_flag[RCCE_IAM], 
+			size, dest, request);
 
-			if(iRCCE_push_send_request(request) == iRCCE_SUCCESS) {
-				return(iRCCE_SUCCESS);
-			}
-			else {
-				iRCCE_isend_queue = request;
+	if(iRCCE_isend_queue == NULL) {
 
-				if(request == &blocking_isend_request) {
-					iRCCE_isend_wait(request);
-					return(iRCCE_SUCCESS);
-				}
-
-				return(iRCCE_PENDING);
-			}
+		if(iRCCE_push_send_request(request) == iRCCE_SUCCESS) {
+			return(iRCCE_SUCCESS);
 		}
 		else {
-			if(iRCCE_isend_queue->next == NULL) {
-				iRCCE_isend_queue->next = request;
-			}
-			else {
-				iRCCE_SEND_REQUEST *run = iRCCE_isend_queue;
-				while(run->next != NULL) run = run->next;      
-				run->next = request;   
-			}
+			iRCCE_isend_queue = request;
 
 			if(request == &blocking_isend_request) {
 				iRCCE_isend_wait(request);
 				return(iRCCE_SUCCESS);
 			}
 
-			return(iRCCE_RESERVED);
+			return(iRCCE_PENDING);
 		}
 	}
+	else {
+		if(iRCCE_isend_queue->next == NULL) {
+			iRCCE_isend_queue->next = request;
+		}
+		else {
+			iRCCE_SEND_REQUEST *run = iRCCE_isend_queue;
+			while(run->next != NULL) run = run->next;      
+			run->next = request;   
+		}
+
+		if(request == &blocking_isend_request) {
+			iRCCE_isend_wait(request);
+			return(iRCCE_SUCCESS);
+		}
+
+		return(iRCCE_RESERVED);
+	}
+}
+
+//------------------------------------------------------------------------------
+// FUNCTION: iRCCE_isend
+//------------------------------------------------------------------------------
+// wrapper function to differentiate between anylength and normal call
+//------------------------------------------------------------------------------
+static iRCCE_SEND_REQUEST blocking_isend_request;
+int iRCCE_isend(
+		char *privbuf,
+		ssize_t size,
+		int dest,
+		iRCCE_SEND_REQUEST *request
+		) {
+	if(request == NULL) request = &blocking_isend_request;
+	
+	if (dest<0 || dest >= RCCE_NP) { 
+		return(RCCE_error_return(RCCE_debug_comm,RCCE_ERROR_ID));
+	}
+	else { 
+		// anylength call
+		if( size < 0 ){
+			// convert size to positive range */
+			int send_size = -size;
+
+			// use header payload
+			if( send_size <= iRCCE_MAIL_HEADER_PAYLOAD ) {
+				iRCCE_init_send_request(privbuf, RCCE_buff_ptr, 
+					RCCE_chunk, &RCCE_ready_flag[dest],
+					&RCCE_sent_flag[RCCE_IAM], 
+					send_size, dest, request);                  
+				request->finished = 1; 
+			
+				iRCCE_mail_send( send_size,
+					iRCCE_ANYLENGTH_PIGGYBACK,
+					0, privbuf, dest );
+				return iRCCE_SUCCESS;
+			}
+			// we need an extra isend-call
+			else {
+				iRCCE_mail_send( send_size, iRCCE_ANYLENGTH,
+					0, NULL, dest );
+				return iRCCE_isend_general( privbuf, send_size,
+					dest, request );
+			}
+		}
+		// normal call
+		else if( size > 0 ) {
+			return iRCCE_isend_general( privbuf, size,
+					dest, request ); 
+		}
+		// do nothing
+		else {
+			iRCCE_init_send_request(privbuf, RCCE_buff_ptr, 
+					RCCE_chunk, &RCCE_ready_flag[dest],
+					&RCCE_sent_flag[RCCE_IAM], 
+					size, dest, request);                    
+			request->finished = 1;                                     
+			return(iRCCE_SUCCESS); 
+		}   
+
+	} 
+
 }
 
 //--------------------------------------------------------------------------------------