Elaborating on the message send semantics as per the ticket

akka-docs/general/index.rst

@@ -5,9 +5,9 @@ General
    :maxdepth: 2
 
    jmm
+   message-send-semantics
    configuration
    event-handler
    slf4j
    addressing
    supervision
-   guaranteed-delivery

akka-docs/general/message-send-semantics.rst

@@ -1,13 +1,14 @@
 
-.. _guaranteed-delivery:
+.. _message-send-semantics:
 
-#####################
- Guaranteed Delivery
-#####################
+#######################
+ Message send semantics
+#######################
 
 
-Guaranteed Delivery
-===================
+
+Guaranteed Delivery?
+====================
 
 Akka does *not* support guaranteed delivery.
 
@@ -39,4 +40,30 @@ application and can solve it fastest and most reliable by explicit ``ACK`` and
 ``RETRY`` (if you really need it, most often you don't). Using Akka's Durable
 Mailboxes could help with this.
 
+Delivery semantics
+==================
+
+At-most-once
+------------
+
+Actual transports may provide stronger semantics,
+but at-most-once is the semantics you should expect.
+The alternatives would be once-and-only-once, which is extremely costly, 
+or atleast-once which essentially requires idempotency of message processing,
+which is a user-level concern.
+
+Ordering is preserved on a per-sender basis
+-------------------------------------------
+
+Actor ``A1` sends messages ``M1``, ``M2``, ``M3`` to ``A2``
+Actor ``A3`` sends messages ``M4``, ``M5``, ``M6`` to ``A2``
+
+This means that:
+    1) If ``M1`` is delivered it must be delivered before ``M2`` and ``M3``
+    2) If ``M2`` is delivered it must be delivered before ``M3``
+    3) If ``M4`` is delivered it must be delivered before ``M5`` and ``M6``
+    4) If ``M5`` is delivered it must be delivered before ``M6``
+    5) ``A2`` can see messages from ``A1`` interleaved with messages from ``A3``
+    6) Since there is no guaranteed delivery, none, some or all of the messages may arrive to ``A2``
+
 .. _Erlang documentation: http://www.erlang.org/faq/academic.html