My own site was once threatened with an RSS listing. In the summer of 1998, I received a message from the RSS group announcing that if our company didn't stop relaying spam, we would be placed on the list. It took a couple of hours to learn what they were talking about, and another day to download, compile, configure, and install a new sendmail. At the same time, I actually felt empowered by the RSS group because I was sick of getting spam myself. Even with relay blocking and blacklisting, spammers find ways to get their cheap messages out.
Most major sites filter incoming email to look for spam and viruses.
Content filters can be programmed to recognize these phrases, and divert them to a quarantine area, where a human can determine whether to forward it to the recipient. Sometimes these systems go overboard. My company's spam filter used to look for triple exclamation points in the Subject field, and one of my gushy friends could never get email to me. Most systems allow some recipients to turn off content filtering. For example, some companies disable content filtering for customer support email accounts, so that customers can rant in a spam-like manner if they feel like it.