KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q105130: SMTP: Err Msg: WARNING Incoming SMTP Mail From Unknown Host

Article: Q105130
Product(s): Microsoft Mail For PC Networks
Version(s): MS-DOS:2.1,3.0
Operating System(s): 
Keyword(s): 
Last Modified: 30-OCT-1999

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Mail Gateway to SMTP, versions 2.1, 3.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

Versions 2.1 and 3.0 of Microsoft Mail Gateway to SMTP may display the following
message in the SMTPGATE.LOG file, and/or the Gateway PC screen:

  [rx] HELO
  <time> WARNING Incoming SMTP mail from unknown host

  Note: Using the undocumented switch -CD with the SMTP gateway provides debug
  information on the gateway screen and log file when full logging is turned on
  with -GACSY and -LACSY command line options.

CAUSE
=====

This warning indicates that section 3.5 of RFC 821 (the "HELO" command is used
to identify the sending host) has been violated. The correct syntax should be:

  [rx] HELO hostname.domain

RESOLUTION
==========

No action is required. The SMTP Gateway will continue to process mail. The
message is merely for your information.

For more information refer to RFC 821.

Additional query words: 2.10 3.00 smtp warning helo

======================================================================
Keywords          :  
Technology        : kbMailSearch kbMailGateSearch kbZNotKeyword3 kbMailGateSMTP300 kbMailGateSMTP210
Version           : MS-DOS:2.1,3.0

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.