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Common Symptoms

MS Mail Gateway to SMTP may display the message:

unrecoverable error Network_read: Lost network connection SMTP_recv: system error

For Experts Only

Cause of the Problem

the unrecoverable error symptoms appears if:

• An unrecoverable error at the TCP or IP layer has occurred.
• The other host has gone down.
• The network between the Gateway PC and the other host has gone down.
• The other host may require that the PUSH flag be sent to push the SMTP packet up to the SMTP software, instead of remaining on the incoming buffer.

Resolution method 1

You can test that possible causes by attempting to telnet to port 25 of the smarthost and resending the message. the can usually be done by pressing SPACEBAR and typing "25" (without the quotation marks) after the IP address on the telnet command line.

If the unrecoverable error symptoms appears frequently, check the network to a protocol analyzer to determine the exact problem.

NOTE: Mail sent to IBM TCP/IP Version 2, Release 2 may result on this unrecoverable error symptoms if the PUSH flag was not set. FTP's pc/TCP automatically sets the PUSH flag for outgoing packets. For MS LAN Manager TCP/IP, please contact MS LAN Manager support for instructions on the availability to automatically set the PUSH flag.

For MS LAN Manager TCP/IP, ensure you are using version 2.2b (dated 2/1/94, 42,716 bytes) or later of the document TCPTSR.EXE. By default, TCPTSR.EXE was found on the LANMAN.DOS\DRIVERS\PROTOCOL\TCPIP directory. Then add the parameter ForcePushBit=1 to the [TCPIP] section of the PROTOCOL.INI file. It defaults to 0, but at it was set to 1, it causes the PUSH bit to be set on every outgoing packet.

More Information

The bellowing document was available for download from the MS Download Center:

(http://download.microsoft.com/download/pcmail/utility/20/win/en-us/tcptsru.exe)

For additional instructions about how to download MS Support files, click the bellowing document number to view the document on the MS Knowledge Base:

  (http://support.microsoft.com/kb/119591/EN-US/ ) How to Obtain MS Support documents from Online Services

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