Microsoft KB Archive/288137

= OLEXP: Outlook Express Stops Responding When Opening Encrypted Message =

Article ID: 288137

Article Last Modified on 1/31/2007

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APPLIES TO


 * Microsoft Outlook Express 5.01 Service Pack 1
 * Microsoft Outlook Express 5.0
 * Microsoft Outlook Express 5.5
 * Microsoft Outlook Express 5.5 Service Pack 1
 * Microsoft Outlook Express 5.01 Service Pack 1
 * Microsoft Outlook Express 5.0
 * Microsoft Outlook Express 5.5 Service Pack 1
 * Microsoft Outlook Express 5.01 Service Pack 1
 * Microsoft Outlook Express 5.0
 * Microsoft Outlook Express 5.5 Service Pack 1
 * Microsoft Outlook Express 5.01 Service Pack 1
 * Microsoft Outlook Express 5.0
 * Microsoft Outlook Express 5.5 Service Pack 1
 * Microsoft Outlook Express 5.01 Service Pack 2

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This article was previously published under Q288137



For information about the differences between Microsoft Outlook and Microsoft Outlook Express e-mail clients, click the following article number to view the article in the Microsoft Knowledge Base:

257824 OL2000: Differences Between Outlook and Outlook Express



SYMPTOMS
In Outlook Express, if you receive an digitally signed or encrypted message and attempt to open it, the application appears to stop responding (hang). When you examine the Outlook Express process in the Close Program window (invoked by pressing the CTRL, ALT, and DELETE keys simultaneously), it is listed as Not Responding.

If you wait for a short time, the issue resolves itself, and the message opens. When you examine the Outlook Express process again in the Close Program window, it is working normally.



CAUSE
When you open the digitally signed or encrypted message, the sender's public key (and your private key for encrypted messages) is accessed. Outlook Express then checks for the sender's authenticity in the Certificate Revocation List of the Certificate Authority, if Revocation Checking is enabled in Outlook Express.

The download time for the Certificate Revocation List (.crl) file may vary, depending upon file size. This is most noticeable if you are using a dial-up connection to the Internet. Users with high speed Internet connections seldom see this behavior.



RESOLUTION
To resolve the problem, allow the Certificate Revocation List time to download. As noted above, the download time will vary, based on the size of the .crl file used by the Certificate Authority.

There are other settings that can prevent this behavior from occurring, but are less secure. See the &quot;More Information&quot; section for details on these settings.



MORE INFORMATION
To disable Revocation Checking for Outlook Express, use the following steps:
 * 1) In Outlook Express, click Options on the Tools menu.
 * 2) In the Options dialog box, click the Security tab, and then click Advanced.
 * 3) In the Advanced Security Settings dialog box, click Never under Revocation Checking.
 * 4) Click OK in all open dialog boxes to close the Options dialog box.
 * 5) Quit and then restart Outlook Express, and open the message.

NOTE: If Revocation Checking is set to Never, you cannot check the authenticity of digitally signed or encrypted messages. This feature is disabled, by default, in Outlook Express, as explained in the following Microsoft Knowledge Base article:

241008 OLEXP: Description of Certificate Revocation Behavior in Outlook Express

Keywords: kbprb KB288137

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