DOCUMENT:Q244346  06-AUG-2002  [exchange]
TITLE   :XCON: Routing Restrictions Don't Work with % Addresses RFC 1123
PRODUCT :Microsoft Exchange
PROD/VER::5.5
OPER/SYS:
KEYWORDS:exc55

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft Exchange Server, version 5.5 
-------------------------------------------------------------------------------

SYMPTOMS
========

The source routing that is specified in Request for Comments (RFC) 1123 5.2.16
allows for addresses to be encapsulated in the recipient part of a Simple Mail
Transfer Protocol (SMTP) address. This enables a person to send an e-mail
address to an SMTP host, and the host then parses the address and reroutes the
message to the intended recipient.

An Internet Mail Service that is set up to receive only messages that are
destined for the SMTP domain name processes source routing messages completely
before it sends back a non-delivery report (NDR).

Messages are completely processed, even if routing restrictions are specified and
a user uses the source routing that is specified in RFC 1123 5.2.16. This may be
the tactic that is used for a denial of service attack on an Internet Mail
Service.

MORE INFORMATION
================

This behavior is by design.



Additional query words: RFC 1123 5.2.16 , source routing, IMS

======================================================================
Keywords          : exc55 
Technology        : kbExchangeSearch kbExchange550 kbZNotKeyword2
Version           : :5.5
Issue type        : kbprb

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 2002.