Spam is sent by both reputable organizations and lesser companies. When spam is sent by reputable companies it is sometimes referred to as "Mainsleaze". Mainsleaze makes up approximately 3% of the spam sent over the internet. The problem with mainsleaze is that it is generally mixed in with mail that the recipients asked for, and it is difficult to tell the difference using traditional mail filters. As a result, if a mail system filters out all the mail from a mainsleazer, they will get complaints from the people who signed up.