550 5.5.0 Invalid EHLO/HELO domain

Posted on 2010-11-18
Medium Priority
Last Modified: 2012-06-22
I'm trying to send an e-mail to a mail server from my Exchange Server 2007 but I got an error:  550 5.5.0 Invalid EHLO/HELO domain

What should I do?

Question by:anovaes
LVL 35

Expert Comment

by:Ernie Beek
ID: 34162898
LVL 33

Expert Comment

by:Dr. Klahn
ID: 34162926
The only thing that follows SMTP HELO or EHLO is the connecting system's fully-qualified name, e.g.

HELO mail.yahoo.com
EHLO smtp.somewhere.org

"Invalid EHLO/HELO domain" is a peculiar way to phrase this error message.  Two possibilities come to mind:

a) It directly refers to the HELO/EHLO fully-qualified name.  The only thing that can be wrong is that the fully-qualified name is somehow unacceptable to the receiving system's SMTP server.

b) It indirectly refers to the fully-qualified name in the HELO/EHLO.  What it really means is "Your name is badly formed," "I can't do an RDNS on your name," or "I've got a blacklist and you're on it."

There are some other possibilities as well.  See the description of SMTP status 550 at this PDF page

LVL 76

Accepted Solution

Alan Hardisty earned 2000 total points
ID: 34163023
Check your SEND connector - look at the General Tab and specifically, the FQDN entered there.  If it ends .local, which it might - that will be your problem.

Change it to something like mail.domain.com to match your MX record and Reverse DNS record, which you should have setup correctly too.

Author Closing Comment

ID: 34260047
That's it.

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