Q258745: XIMS: Internet Mail Service Displays SMTP Banner Slowly
Article: Q258745
Product(s): Microsoft Exchange
Version(s): winnt:5.5
Operating System(s):
Keyword(s): exc55
Last Modified: 11-JUN-2002
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The information in this article applies to:
- Microsoft Exchange Server, version 5.5
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IMPORTANT: This article contains information about modifying the registry. Before you
modify the registry, make sure to back it up and make sure that you understand how to restore
the registry if a problem occurs. For information about how to back up, restore, and edit the
registry, click the following article number to view the article in the Microsoft Knowledge Base:
Q256986 Description of the Microsoft Windows Registry
SYMPTOMS
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After you make a connection to an Exchange Server computer Internet Mail Service
on port 25, the Simple Mail Transfer Protocol (SMTP) banner may not be displayed
quickly, which may cause certain SMTP applications to time out.
CAUSE
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This issue can occur because Exchange Server performs a reverse lookup on all
connections. A reverse lookup may take several seconds because of a lack of or
incorrectly configured Domain Name System (DNS) servers.
RESOLUTION
==========
To resolve this issue, increase Internet Mail Service performance by disabling
reverse resolution. To do this, you need to edit the registry.
WARNING: If you use Registry Editor incorrectly, you may cause serious problems
that may require you to reinstall your operating system. Microsoft cannot
guarantee that you can solve problems that result from using Registry Editor
incorrectly. Use Registry Editor at your own risk.
If you use Regedit.exe:
1. Start Registry Editor (Regedt.exe).
2. Locate the following key in the registry:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeIMC\Parameters
3. On the Edit menu, click New DWORD Value.
4. Type "DisableReverseResolve" (without the quotation marks).
5. Under "Value data", type "1" (without the quotation marks).
6. Quit Registry Editor.
If you use Regedt32.exe:
1. Start Registry Editor (Regedt32.exe).
2. Locate the following key in the registry:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeIMC\Parameters
3. On the Edit menu, click Add Value, and then add the following registry value:
Value Name: DisableReverseResolve
Data Type: REG_DWORD
Radix: Binary
Value: 1
4. Quit Registry Editor.
MORE INFORMATION
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Reverse resolution occurs when the name of the host that delivered an incoming
SMTP message is resolved and placed in the message header by the Internet Mail
Service. When reverse resolution is disabled, the Internet Mail Service does not
resolve the host name in the upper-most Received From field of the SMTP message
header. If the address is in Internet Protocol (IP) form, it remains in IP form.
Additional query words: Smart Host, IMS
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Keywords : exc55
Technology : kbExchangeSearch kbExchange550 kbZNotKeyword2
Version : winnt:5.5
Issue type : kbprb
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