Email block listing is a process used by organisations' email system to determine if emails should be rejected or accepted based on a predefined set of rules, such as where the emails are being sent from.

Some of these block lists update automatically and from time to time they can add people to their block lists in error. Unfortunately for the person or organisation that may have been added, they will not be aware of the fact until they try and send an email and find that the email has been rejected.

What causes a person or organisation to appear on a block list?

Organisations that do not protect their email systems adequately are open to having their systems unknowingly exploited. The most common example is where a person relays spam email through an unprotected email system in order to make the origin of the email harder to trace. On a smaller scale, a home computer may be infected with a Trojan virus that propagates itself by sending email to everyone in the email address book on that computer. For every email successfully received by someone in that address book, the virus will perform the same action again on the next computer resulting in an exponential spread of the virus. This is one of the many reasons why it's important for home users to install security software such as antivirus and firewall applications and keep them updated.

In either of these scenarios large amounts of spam email are generated and this is recognised by companies that create block lists. However as mentioned earlier, the methods and logic used to identify potential spam threats are not 100% perfect and it's possible for unwarranted block listing to occur.

How do I know if I've been block listed?

Whenever an email is rejected, for any cause, it will be returned to the sender. The reasons behind the emails rejection will be noted in the email that's returned. The most common wording you'll see in an email that's been rejected due to block listing is:

Diagnostic code: smtp;554

This in turn may be followed by the name of the company that created the block list that identified your email as spam. Some of the more popular companies include:

• SORBS
• SpamCop
• SpamHaus
• NJABL.org

What can I do if I've been block listed?

We will attempt to resolve block listing issues but unfortunately we have no official agreement with companies that produce block lists to get people or organisations delisted. Only those who create and use block lists have this ability.

We endeavour to settle these matters on a best efforts basis and can't make any promises as to when or if an individual block listing issue can be resolved. There are however some things that you can do to help.

• Forward examples of the rejected messages to help@clear.net.nz  along with a short description of the issue. This will help us identify and build on examples of supporting information in order to get people or organisations delisted.
• Try to get in contact with the user of the block list to negotiate a delisting. This can be difficult to do but sometimes persistence can pay off. If you decide to go down this route and want to email the comp