Exchange Server cannot communicate with Internet Information Server over Secure Sockets Layer

The Internet Information Server (IIS) SMTP Service does not recognize the STARTTLS command that the Exchange Server 5.5 computer issues. The SMTP Protocol log on the Exchange Server computer shows that Exchange Server is giving the STARTTLS command. Next, the IIS SMTP Service responds with "220 SMTP server ready" (which is normal). Exchange Server follows by issuing the MAIL FROM command to IIS. IIS immediately generates errors by returning a "505 Must issue a STARTTLS command first" error. Then Exchange Server issues a QUIT command, and the IIS SMTP Service closes the connection. The first message that is sent from an Exchange Server computer and forwarded to the IIS SMTP Service generates a non-delivery report (NDR). A second message sent from the same Exchange Server computer and forwarded to the same SMTP Service goes through. This problem does not occur until the 128-bit encryption is enabled on the IIS 4.0 Default SMTP Site Properties page on the SMTP Service.

A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Microsoft Windows NT service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question. The English version of this fix should have the following file attributes or later:

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.