Microsoft KB Archive/329918

= OL2002: Cannot Send Outgoing Mail =

PSS ID Number: 329918

Article Last Modified on 6/28/2004

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The information in this article applies to:


 * Microsoft Outlook 2002
 * Microsoft Outlook 2000
 * Microsoft Outlook Express 6.0 for Windows XP
 * Microsoft Outlook Express 6.0 for Windows 2000
 * Microsoft Outlook Express 5.5 for Windows 2000
 * Microsoft Outlook Express Version 6 for Windows 98 Second Edition
 * Microsoft Outlook Express 5.5 for Windows 98 Second Edition
 * Microsoft Outlook Express 6.0 for Windows Millennium Edition
 * Microsoft Outlook Express 5.5 for Windows Millennium Edition

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This article was previously published under Q329918



SYMPTOMS
When you try to send mail by using any of the programs that are listed in the beginning of this article, you may experience one or more of the following symptoms:  Your e-mail program responds very slowly or stops responding (hangs) during the send/receive process. The e-mail message you are trying to send is not sent, and stays in the Outbox folder. You receive an error message that is similar to one or more of the following error messages:

An unknown error has occurred,, lost connection to

An unknown error has occurred server error 421,, lost connection to port 25, 0x800ccc67

Your server has unexpectedly terminated the connection. 0x800ccc0f.

Connection to the server was interrupted,, lost connection to computer,   0x800ccc0F



Note These symptoms are only related to outgoing mail. Incoming mail may be unaffected by these symptoms.



CAUSE
This issue may occur if both of the following conditions exist:
 * Your computer or your network is connected to the Internet by using a Linksys BEFSR41, BEFSR81 or BEFW11S4 router.
 * The e-mail message you are trying to send contains an attachment, or was composed by using Microsoft Word.

The default maximum transmission unit (MTU) on many devices is set higher than the MTU of the various routers or devices between the user and their mail provider. The problem is not necessarily the Linksys device. There may be a misconfigured router in the path between the user and the mail provider that does not allow packets larger than a certain size to pass through.



RESOLUTION
To resolve this issue, change the MTU setting for your router. For information about how to do this, view the documentation that is included with your router, or visit the following Linksys Web site:

http://www.linksys.com/support/support.asp?spid=87

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.



MORE INFORMATION
For additional information on troubleshooting &quot;black hole&quot; router issues, click the following article number to view the article in the Microsoft Knowledge Base:

314825 How to Troubleshoot Black Hole Router Issues

For additional information on issues mentioned in the Resolution section of this article, click the following article number to view the article in the Microsoft Knowledge Base:

159211 Diagnoses and Treatment of Black Hole Routers

For additional information on issues mentioned in the Symptoms section of this article, click the following article number to view the article in the Microsoft Knowledge Base:

156438 Internet Mail or News Reader Software Hangs or Times Out

Changing the MTU setting on the router will force the computers behind the router to limit their packet size to a size of less than the standard of 1,500 bytes. Many internet providers recommend something around 1,380 bytes to be certain.

Keywords: kbprb KB329918

Technology: kbOutlook2000Search kbOutlook2002 kbOutlook2002Search kbOutlookExpress500WinME kbOutlookExpress550Win2000 kbOutlookExpress550Win98SE kbOutlookExpress600Win2000 kbOutlookExpress600Win98SE kbOutlookExpress600WinME kbOutlookExpress600WinXP kbOutlookExpress600WinXPSearch kbOutlookExpress98Search kbOutlookExpressSearch kbOutlookExpressWin2000Search kbOutlookExpressWinMESearch kbOutlookExpressWinXPSearch kbOutlookSearch kbZNotKeyword3

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