Article: Q241892
Product(s): Microsoft Exchange
Version(s): winnt:5.0,5.5
Operating System(s):
Keyword(s): exc5 exc55
Last Modified: 06-AUG-2002
-------------------------------------------------------------------------------
The information in this article applies to:
- Microsoft Exchange Server, versions 5.0, 5.5
-------------------------------------------------------------------------------
SYMPTOMS
========
When sending e-mail to a third-party SMTP server or through a firewall, a
non-delivery report (NDR) similar to the following may be generated:
Subject: Notification: Outbound Mail Failure - A protocol error occurred.
A mail message was not sent due to a protocol error.
501 syntactically invalid HELO argument(s)
The message that caused this notification was:
CAUSE
=====
This error is generated by a third-party SMTP server or firewall.
When the Microsoft Exchange Internet Mail Service establishes a connection to a
remote host, the Internet Mail Service initiates the SMTP conversation with
"EHLO <domainname.com>". If an error is returned, the Internet Mail
Service falls back to "HELO <domainname.com>". If the HELO command returns
an error, an NDR is generated containing the error.
Additional query words:
======================================================================
Keywords : exc5 exc55
Technology : kbExchangeSearch kbExchange500 kbExchange550 kbZNotKeyword2
Version : winnt:5.0,5.5
Issue type : kbprb
=============================================================================