XFOR: NDR with Error 501 Syntactically Invalid HELO Argument(s) (241892)
The information in this article applies to:
- Microsoft Exchange Server 5.0
- Microsoft Exchange Server 5.5
This article was previously published under Q241892 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.
| Modification Type: | Minor | Last Reviewed: | 4/28/2005 |
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| Keywords: | kbprb KB241892 |
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