Microsoft Outlook Error 0x800CCC0F sending mail

0x800CCC0F or 0x8004210A is Microsoft's catch-all error message in Outlook//Outlook Express for anything that interrupts the sending of email on a client machine. The most common causes of this error are your ISP blocking port 25, antivirus email scanning (especially with Norton/Symantec Antivirus) or personal firewall software (especially Norton Internet Security).

You can try the following steps to see if this is causing the problem:
1. Follow knowledge base article 762 to use our alternate SMTP port.
2. Temporarily disable your antivirus email scanning and send a test message.
3. Temporarily disable your entire antivirus software and send a test message.
4. Temporarily disable your personal firewall software and send a test message.

If none of these steps work, other possible causes of this problem can be found at http://support.microsoft.com/default.aspx?scid=kb;en-us;813514

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