Spam is the cheapest method to advertise a product, as it costs only $100 (more or less) for a list of 30 million e-mail addresses. With that and a fast Internet connection, yeah! You can become an immediate spammer. And statistics show that even though most people ignore spam, a small percentage actually send their money to the spammer. That small percentage adds up to real money when you’re talking about millions of attempts.
Open relay servers are mail servers that are configured to accept relay requests from anyone, thus allowing anyone on the Internet to send e-mail to all domains anywhere without traceability. Such relays exist because of misconfigured or default server settings, or hacked computers on which mail server software has been installed.
Another popular choice for spammers to hide their identities is to use an open proxy. Open proxies are computers that enable Internet users to relay data through them, showing the destination host the IP address of the proxy and not of the connecting computer. The spammers load their spamming software with a list of open proxies on the Internet, which can be acquired easily from different sites that maintain updated proxy lists. The software checks the proxies and generates a working list. The software then cycles the list and uses the proxies as relays for e-mail connections to send spam. The recipient sees only the proxy’s IP address and has no way of knowing the spammer’s original IP address—in fact, there’s no indication that the proxy wasn’t the real source.