Require HELO identifier

Normally, the reason you have reached this page is because a mail server has sent you a message when it rejected an email from you, or one of your users.

  • If you are an email or network operator, you can continue reading this section
  • If you are a user sending email and it got blocked, you should read this section instead

Information for Email and Network Operators

Although email servers can (by RFC) accept connections that have no HELO identifier, most email servers and anti-spam tools will not allow this behaviour. This practice does not supply enough information to safely identify the server and responsible party, if a problem email is received. And almost every mail server offers this capability. This is a simple rule which just insists that the HELO (or EHLO) is sent with every email connection. However, you should ensure that the HELO is also properly formatted.

In order to ensure that messages are not stopped by this check, make sure the HELO or EHLO is issued by your server or scripts.

An example would be: ESMTP

Spammers, bulk mailers, and trojans and bots often do not handle the HELO portion correctly, and this makes spam detection easier, and also helps you identify exactly what server was causing a problem. Many email administrators who buy off the shelf mail server software may not correctly set up the HELO, and instead it may default to just a generic identifier, or not be sent. Ensure that you correctly configure your mail server. If you are the one sending the message, and you were blocked with this message, it is most likely that your email provider has not set up the mail server according to best practices, however read the section below.

Information for users. Why was my email blocked?

If your email was blocked, and the link sent you here it is probably not your fault. It is usually the fault of your outgoing email server, however it can be caused by other reasons:

  • Automatic notices that were poorly programmed
  • Bad or very old Email software
  • Your ISP or Email provider (outgoing mail server)

Normally, this rule will only block spammers who don’t, or can’t change the functionality of the tool they are using to send spam, or by pass sending this to avoid detection by some spam softwares.

For help on this you should contact your email administrator.