XFOR: Internet Mail Service Very Slow with High Message Volume |
The information in this article applies to:
-
Microsoft Exchange Server, versions 5.0, 5.5
SYMPTOMS
You may experience either of the following symptoms:
- When an extremely large number of Simple Mail Transfer Protocol (SMTP)
messages are sent through the Internet Mail Service and the Internet
Mail Service is unable to resolve some of the Domain Name System (DNS)
addresses associated with the messages, the Internet Mail Service may
take a long time to send the messages.
-OR-
- When the outbound Internet Mail Service message queue contains a large
number of messages, the Internet Mail Service may take an unusually
long time to start.
CAUSE
These problems can occur for the following reasons:
- The rate at which the Internet Mail Service delivers SMTP messages is
limited in part by the number of resolver threads and SMTP worker
threads that are available. If message volume is very high and DNS name
resolution is frequently unsuccessful, the number of available threads
can become very low.
- When you start the Internet Mail Service, it processes the destination
domain list. The method by which it processes the destination domain
list can be inefficient, particularly when the outbound message queue
contains a large number of messages.
WORKAROUND
You can increase the number of resolver threads and SMTP worker threads
that are available when the Internet Mail Service starts, but only by
increasing the value assigned to the ThreadsPerProcessor variable.
STATUS
Microsoft has confirmed this to be a problem in Microsoft Exchange Server
version 5.0.
A supported fix is now available, but has not been fully regression-tested
and should be applied only to systems experiencing this specific problem.
Unless you are severely impacted by this specific problem, Microsoft
recommends that you wait for the next service pack that contains this fix.
Contact Microsoft Technical Support for more information.
This fix has been posted to the following Internet location:
ftp://ftp.microsoft.com/bussys/exchange/exchange-public/fixes/Eng/Exchg5.0/Post-SP2-IMS/
Microsoft has confirmed this to be a problem in Microsoft Exchange Server
version 5.5. This problem has been corrected in the latest U.S. service
pack for Microsoft Exchange Server version 5.5. For information on
obtaining the service pack, query on the following word in the Microsoft
Knowledge Base (without the spaces):
S E R V P A C K
MORE INFORMATION
After you apply the fix, three new registry values are available under the
following registry key:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeIMC
\Parameters
NOTE: The above registry key is one path; it has been wrapped for
readability.
The following registry values are available:
Value Name Value Type Description
-----------------------------------------------------------------------
SMTPWorkerThreads REG_DWORD If this registry value exists, it
represents the number of SMTP worker
threads that are available when the
Internet Mail Service starts.
ResolverThreads REG_DWORD If this registry value exists, it
represents the number of resolver
threads that are available when the
Internet Mail Service starts.
DestDomainThreshold REG_DWORD If this registry value exists, it
represents the number of
DestinationDomain objects that are
cached before the Internet Mail
Service attempts to reduce the size
of the destination domain list.
Additional query words:
ims internet mail connector imc
Keywords : XFOR
Version : WINDOWS:5.0,5.5
Platform : WINDOWS
Issue type : kbbug
