Mail flow stops when you install the Microsoft POP3 Service on a server that is running Exchange Server 2003

When you install the Microsoft POP3 Service on a server that is running Microsoft Exchange Server 2003, Simple Mail Transfer Protocol (SMTP) mail flow stops for both incoming mail and outgoing mail.

Additionally, the following event may be logged in the Application log:

Event Type: Error
Event Source: MSExchangeTransport
Event Category: NDR
Event ID: 3008
Description:
A non-delivery report with a status code of 5.0.0 was generated for recipient rfc822 <User@domain.com>

The Microsoft POP3 Service is a Microsoft Windows Server 2003 service. However, the Microsoft Exchange POP3 Service is an Exchange Server 2003 service. These services conflict with each other.

To resolve this problem, use the Add or Remove Programs tool to remove the Microsoft POP3 Service. To do this, follow these steps:

1. Click Start, click Run, type appwiz.cpl, and then click OK.
2. Click Add/Remove Windows Components.
3. In the Windows Components Wizard, click to clear the E-mail Services check box, click Next, and then click Finish.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

For more information, click the following article number to view the article in the Microsoft Knowledge Base: