IP addresses are added to the MAPS OPS because they are insecure proxy servers that have transmitted spam. An open proxy is where a machine will accept a connection on a specific port, and can then be used to connect to another machine to send mail. There are legitimate proxy servers out there, and you may be using one without even knowing it.

The problem with open proxies that are insecure is that they allow for anybody in the world to use them to connect to the recipient's machine and deliver the spam. Unlike open relays, open proxies do not record the originating IP address in the headers of the mail being sent, and typically there are not logs being kept on the open proxy so it makes tracking down the actual spam source/origin difficult.

Many email administrators choose to use our list to refuse mail from IP addresses on this list until they are fixed and are no longer insecure proxies that can be used to send spam.

You need to contact your ISP (the company you pay for internet access). Write them or call them and tell them that you're having trouble with your email, explain to them that you received this error message, and ask them to visit our web site. If the server is owned by your school or employer, then contact the folks that run the server and explain the same thing to them.

We know that email is important to you, and we want to help the owners and administrators of the listed IP addresses secure the open proxies and correct the problem. Correcting this problem is usually a very simple process, involving the admin changing a few lines of one configuration file, or ticking a checkbox on a configuration form.