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Trouble Sending Email / SMTP Error 450: Helo command rejected

        If you are having trouble sending email to an email address at MailMax Direct or any of the AGI Companies, you may be experiencing something similar to the following:

SMTP ERROR 450 <...>: Helo command rejected: Host not found.

        This is a result of your mail server reporting invalid, false, or otherwise unverifiable information while attempting to deliver the message to our mail server, and nine times out of ten, your administrators are simply unaware of the problem. So before panic or any other rash emotion sets in, read on to get a basic understanding of what is happening and how you can help fix the problem *without being a wiz!

        Have you ever heard of an underage person attempting to use a fake ID when entering bar? Or perhaps you have heard of a person using fake or stolen ID to gain access to a secured area? Unfortunately, abuse of the HELO command has become the Internet equivalent, except this time it's about unwanted dangerous email containing viruses and malicious programs, or extreme volumes of unsolicited advertisement email clogging up the mail servers of the Internet and our emailboxes otherwise known as spam.

        When you send an email message on the Internet, your mail server uses the SMTP protocol to communicate with our mail server in an attempt to deliver the message. Our mail server, like most on the Internet, attempts to filter out unsafe or unsolicited email. One of the many ways it does this is by inspecting the HELO or EHLO command given by the sending mail server. The HELO command is typically the first command given by the sending mail server. The syntax for this command is:

HELO my.mailserver.tld

        In that example, my.mailserver.tld would be the proper fully qualified hostname of the sending mail server. Our mail server inspects this hostname to make sure it is a legitimate hostname on the Internet. A large percentage, if not the majority of unsafe and unsolicited email, is sent using an illegitimate or fake hostname, in order to hide the true identify of the sender. This is done by simply making up a hostname such as "abc.efg123.com" and then giving that to our server via the HELO command. Our server checks that the hostname given in the HELO command has either an A or MX record in a DNS server(s) on the Internet. If it does not have at least one of those entries, the chances are the email message is illegitimate and will be rejected.

        Reasons for not having an A or MX record in DNS for a mail server could be 1) the sender of the email or the administrator of that mail server or the organization owning that mail server want to hide their identity, 2) the mail server's configuration has a typo in the name to be given during the HELO command, or 3) the administrator is unaware the mail server software is reporting an incorrect address during the HELO command. For those mail servers falling under reason #1, it is a hopeless cause and we will not be blindly accepting email from a mail server forging it's HELO hostname any time soon. For those mail servers falling under reason #2 or #3, the administrator of the mail server can easily fix the problem by creating a proper A or MX record in the DNS server(s) for their domain(s). Information on DNS A and MX records is available at Wikipedia.org.

If you are receiving the error above when sending email to us, please do the following:

1. Contact the organization, department, or person responsible for the mail server which you are using. This may be someone within your organization if your organization owns it's own mail server, or it may be your Internet Service Provider if they are providing email services to you.
2. Forward them to this page, http://www.mailmaxdirect.com/cs_smtp450.html and ask them if there might be a misconfiguration or discrepancy in the setup of the mail server or the DNS server(s) with regard to the hostname being given in the HELO command.
3. If they find that yes, there was either a misconfiguration with the mail server, or the A or MX or both records were missing in DNS, ask them to fix it by either correcting the hostname being given in the HELO command to the proper hostname, or creating the proper A, MX or both records in DNS. Once they have corrected the problem, you should be able to send email within 24 to 48 hours or as long as it takes for the changes to take effect.
4. If they have a legitimate reason for giving false information in the HELO command, or are unwilling to correct the problem, you may either choose to use another mail server or ISP if necessary, or request a special exception from MailMax Direct to allow this particular mail server to deliver mail. Special exceptions will only be granted to customers of MailMax Direct or the AGI Companies, and only if it is determined the problematic mail server is owned by the customer's organization and is not being used for illegitimate email. Please request a special exception with your CSR. Keep in mind that if you are receiving this error when sending email to us, this may also be the cause of other email troubles you are having, have had, or will have in the future, even with different error messages from other mail servers. It would be best to correct the problem as a whole rather than requesting an exception workaround.

Thank you for your cooperation,
The MailMax Direct and AGI mail servers :)

* About the non-wiz part: Want to quickly fix the problem without getting involved? Easy, forward this to your IT department or whoever is handling the administration of your mail server. They can either come back to you and say "Aha, we fixed it!" or "No, we like trying to hide our identity on the Internet. Tough beans." If their answer is the latter, see step #4 above.