If you are on the Spam Eating Monkey Blacklist, there could be any number of issues that need to be addressed in your network: virus-generated spam, dynamic IP addresses previously used by spammers, or bulk mail sending that does not comply with the CAN-SPAM Act.
Sem Black Reports Sources Of Spam
Spam-based Blacklists are those that will list either single IP Addresses or entire ranges that have actually received Spam, i.e. Unsolicited Bulk Email (UBE) in their Spamtraps from an IP-Address. This could be a result of a compromised email account, an Open Relay, or simply sending mass emails / marketing and not following best practices according to the "CAN-SPAM Act of 2003" (ref: https://en.wikipedia.org/wiki/CAN-SPAM_Act_of_2003)
Sem Black Automatically Delists Entries
This blacklist does not offer any form of manual request to delist. Your IP Address will either automatically expire from listing after a given timeframe, or after time expires from the last receipt of spam into their spamtraps from your IP Address.