For information about the differences between Microsoft Outlook Express and Microsoft Outlook 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
The Outlook Express Client may not be able to send mail to or receive mail from Microsoft Exchange Server 5.0 or 5.5. On Exchange Server, you will see only one warning message:
Event ID: 11103 Description: POP3 connection to 188.8.131.52 lost.Enabling logging on the Exchange Server computer for the POP3 protocol reveals the following informational message just before the warning.
Event ID: 11300 Description: An unauthenticated POP3 client 184.108.40.206 issued the following command: AUTH .From Outlook Express version 4.72.2106.4, you see a Connection Failure dialog box. If you click Details, you will find the following information:
* Unable to logon to the server using Distributed Password Authentication. Account'Work POP3 Server', Server:'Server.Domain.com',Protocol: POP3,Server Response:'.',Port: 110, Secure(SSL):No, Error Number: 0x800CCC18
The client is trying to use Secure Password Authentication and it is not enabled on the Exchange Server computer. To verify what form of authentication the Outlook Express client is using, in Outlook Express, on the Tools menu, click Accounts, and click the Server tab for the account that failed.
To work around this problem, enable Windows NT Challenge/Response authentication on the server for clients that want to use Secure Password Authentication, or use the Log on using option in Outlook Express.
For additional information about enabling Windows NT Challenge/Response, please see the following article in the Microsoft Knowledge Base:
192510 Where to enable NT challenge response for POP3In regards to the 0x800CCC18 error number in Outlook Express, it may also appear when using Secure Password Authentication on a client with Windows NT Challenge/Response already enabled and functioning correctly. For additional information, please see the following article in the Microsoft Knowledge Base:
198704 You receive error 0x800ccc90 or error 0x800ccc18 when you try to log on to Exchange Server by using Secure Password Authentication