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Q237327: XIMS: STARTTLS Advertised Even If SSL Certificate Not Available

Article: Q237327
Product(s): Microsoft Exchange
Version(s): 2.0,4.0,5.5 SP2
Operating System(s): 
Keyword(s): exc55sp2 EXC55SP3Fix kbExchange550preSP4fix kbExchange550sp4Fix
Last Modified: 11-NOV-2000

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The information in this article applies to:

- Microsoft Exchange Server, version 5.5 SP2 
- Microsoft Commercial Internet System version 2.0 
- Microsoft Internet Information Server 4.0 
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SYMPTOMS
========

When responding to an EHLO command, the Simple Mail Transfer Protocol (SMTP)
service included with the Microsoft products listed at the beginning of this
article always indicates that it supports the STARTTLS command, even if no
Secure Sockets Layer (SSL) certificates are available for the connection. If an
SMTP client sends a STARTTLS command to the server when no SSL certificates are
available, the following entry appears in the SMTP log file (Smtp.log):

  554 Unable to initialize security subsystem

If the SMTP client is connected to the server through a firewall, the firewall
may respond to the STARTTLS command itself, instead of passing the command to
the server. This causes the client to use encryption, even though the server is
not configured to support it. As a result, the client is unable to send messages
across the connection. This behavior is known to occur with the Cisco PIX
Firewall and Secure Computing Sidewinder Security Server firewall, but it may
also occur with other firewalls.

RESOLUTION
==========

Exchange Server 5.5
-------------------

Exchange Server Computer Is Not Operating Behind a Proxy Server:

To resolve this problem, obtain the latest service pack for Exchange Server
version 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


Exchange Server Computer Is Operating Behind a Proxy Server:


To resolve this problem, obtain the latest service pack for Exchange Server
version 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 the Microsoft products that are
listed at the beginning of this article.

Exchange Server Computer Is Not Operating Behind a Proxy Server:

This problem was first corrected in Exchange Server 5.5 Service Pack 3.

Exchange Server Computer Is Operating Behind a Proxy Server:

This problem was first corrected in Exchange Server 5.5 Service Pack 4.


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

Certificates are configured using the Internet Information Service (IIS) Key
Manager program. In IIS, certificates can be applied to all Internet Protocol
(IP) addresses, one particular IP address, or no IP addresses. In Microsoft
Commercial Internet System (MCIS), certificates can be bound to one particular
IP address or all unassigned IP addresses. In MCIS, certificates can also be
bound to one particular Transmission Control Protocol (TCP) port or all
unassigned TCP ports. The SMTP service indicates that it supports TLS even if
the IP address and TCP port you are connected to do not have an associated
certificate.

After you apply the fix, the SMTP service only indicates that it supports TLS if
the IP address and TCP port you are connected to has an associated certificate.

For additional information about configuring Exchange Server to operate behind
Proxy Server 2.0, click the article number below to view the article in the
Microsoft Knowledge Base:

  Q181847 XADM: How to Configure Microsoft Exchange Server with Proxy Server

The third-party products discussed in this article are manufactured by vendors
independent of Microsoft; we make no warranty, implied or otherwise, regarding
these products' performance or reliability.

Additional query words:

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Keywords          : exc55sp2 EXC55SP3Fix kbExchange550preSP4fix kbExchange550sp4Fix 
Technology        : kbiisSearch kbAudDeveloper kbExchangeSearch kbiis400 kbZNotKeyword2 kbMCISSearch kbMCIS200 kbExchange550SP2
Version           : :2.0,4.0,5.5 SP2
Issue type        : kbbug
Solution Type     : kbfix

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