XFOR: Server Advertises STARTTLS Even Though SSL Certificate Not Available

ID: Q237327

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 version 4.0

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

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

The English version of this fix should have the following file attributes or later:

Component: Internet Mail Service

File name	Version
Msexcimc.exe	5.5.2648.0

STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article. This problem was first corrected in Exchange Server 5.5 Service Pack 3.

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.

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

Additional query words:

Keywords : prodmcis2 prodIMS exc55sp2 EXC55SP3Fix
Version : winnt:2.0,4.0,5.5 SP2
Platform : winnt
Issue type : kbbug