DOCUMENT:Q267245  10-NOV-2000  [exchange]
TITLE   :XIMS: Internet Mail Service Returns NDR or Silently Drops E-Mail
PRODUCT :Microsoft Exchange
PROD/VER:winnt:5.5
OPER/SYS:
KEYWORDS:exc55 kbExchange550preSP4fix kbExchange550sp4Fix

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The information in this article applies to:

 - Microsoft Exchange Server, version 5.5 
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SYMPTOMS
========

When you send an e-mail message, if the Domain Name System (DNS) records for a
target domain are unreachable or a remote server denies the Internet Protocol
(IP) address of the Exchange Server computer, the Internet Mail Service may
either silently drop the e-mail message or incorrectly return a non-delivery
report (NDR) message without trying to send the message again. This occurs even
though the Internet Mail Service should try to send the e-mail message again,
because at least one IP address may be temporarily unreachable.

CAUSE
=====

This issue can occur if the Exchange Server computer incorrectly sets retry for
an outbound message when there are several mail exchanger (MX) records for a
target domain in DNS.

RESOLUTION
==========

To resolve this problem, obtain the latest service pack for Exchange Server 5.5.
For additional information, please see the following article in the Microsoft
Knowledge Base:

   Q191014 XGEN: How to Obtain the latest Exchange Server 5.5 Service Pack



STATUS
======

Microsoft has confirmed this to be a problem in Microsoft Exchange Server
version 5.5. This problem was first corrected in Exchange Server 5.5 Service
Pack 4.


Additional query words: IMS

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Keywords          : exc55 kbExchange550preSP4fix kbExchange550sp4Fix 
Technology        : kbExchangeSearch kbExchange550 kbZNotKeyword2
Version           : winnt:5.5
Issue type        : kbbug
Solution Type     : kbfix

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