Information Systems & Services (ISS) - Rejected Mail helo

Information Systems & Services (ISS)


Rejected Mail 'helo'

When mail servers communicate with each other they must introduce themselves correctly. They do this using a 'HELO' command. Quite often spammers do this incorrectly.

    RCPT TO: <> Received 504 <MailServer>:
    Helo command rejected: need fully-qualified hostname

In the above example the sending host claimed that it's Internet name was MailServer. This is not correct. The name MUST be what is called a Fully Qualified Domain Name (FQDN). An example of a correct name response would be

What to do ?

As a mail sender this is out of your control. You should contact your own mail administrator/provider with this information.