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Q244346: XCON: Routing Restrictions Don’t Work with % Addresses RFC 1123

Article: Q244346
Product(s): Microsoft Exchange
Version(s): 5.5
Operating System(s): 
Keyword(s): exc55
Last Modified: 06-AUG-2002

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The information in this article applies to:

- Microsoft Exchange Server, version 5.5 
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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

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

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