You receive the"0x800CCC69 SMTP_550_MAILBOX_NOT_FOUND" error message or the "503 Sender already specified" error message when you try to send an e-mail message in Outlook Express or in Outlook on a computer that is running Windows XP Home Edition (873022)



The information in this article applies to:

  • Microsoft Outlook Express 6.0
  • Microsoft Office Outlook 2003
  • Microsoft Outlook 2002
  • Microsoft Outlook 2000

SYMPTOMS

When you use Microsoft Outlook or Microsoft Outlook Express on a computer that is running Microsoft Windows XP Home Edition to send a new e-mail message, you may experience the following symptoms:
  • In Outlook, you may receive the following error message:

    Unable to deliver the message due to a communication failure ......... 503 Sender already specified.
  • In Outlook Express, you may receive the following error message:

    error: 0x800CCC69 SMTP_550_MAILBOX_NOT_FOUND

CAUSE

This issue may occur if the firewall settings in the Freedom program from Zero-Knowledge Systems Inc. are not configured correctly on your computer.

MORE INFORMATION

You may contact Zero-Knowledge Systems Inc. if you require help in configuring the firewall in Freedom program so that it is compatible with Outlook and Outlook Express.

For additional information about Freedom program, visit the following vendor Web sites:

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.
Microsoft provides third-party contact information to help you find technical support. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information.

Modification Type:MinorLast Reviewed:9/15/2004
Keywords:kbinfo kbtshoot kbprb KB873022 kbAudITPRO