Spam selling lists of millions of email addresses is very common, now we seeing spam selling lists of open relays. The message in question started its sales-pitch, "Sick and tired of always looking for good open relay mail servers?" and offered, "thousands of good ones", "checked every hour" to be "delivered to your inbox every day for only $25 /mnth".
What does this mean? Those familiar with email systems and open relay blacklists can skip to the next paragraph. Normally, when you send email, your computer connects to your local mail server (in your office, or at your ISP) and gives it the message, with the destination address. That mail server looks up the location of the destination mail server, connects to it and delivers the message. When email is sent to you, your local mail server receives the message and puts it in your mailbox, ready for you to read when convenient. So, normally, your local mail server will be handling messages that either originate from or are addressed to your organisation (or both). What happens when your mail server receives a message that neither originates from or is addressed to your organisation? Many mail servers are configured to refuse the message, a mail server that accepts and delivers the message is called an Open Relay. Spammers love Open Relays, they can send an open relay one message, with hundreds or thousands of destination addresses, and it will happily deliver their spam. The bandwidth of the owner of the open relay gets used, not the spammers, and it helps the spammer conceal the source. Because of this, there are blacklists of open relays published, and some organisations (Yui Kee included), refuses connections from mail systems on those lists - this might be expressed as a policy, like: "You must secure your mail server against abuse by spammers before attempting to send us email".
Sometimes, the legitimate users of open relay mail systems complain about their email being blocked ("Why have you blocked my message?, This is against Free Speech!"). Explaining what the spammers are doing, stealing their bandwidth, and how they can fix it, does not always help, ("I cannot be expected to understand these obscure technical details!"). Now we can give these confused victims a message with a dollar sign: Spammers are selling other spammers the address of your mail server, so that they can abuse it too. Wake up - someone is making money from your mail server, and it is not you!