Mailhosts Shortlist is and IP based blacklist. It only lists IPv4 addresses. Listings are created automatically by the Shortlist in response to spam received by a subset of Mailhosts.org spamtraps.
Similarly, all delistings are automatic as well. There are no manual removals nor additions.
They create a score for each IP based on the number of trap hits over the preceeding 72 hour period. Older hits are scored lower than newer hits. Any IP with a score over a certain threshold is automatically included when the zone is rebuilt.
The zone is rebuilt every 30 minutes. Therefore the theoretical longest that an IP can remain listed after the spam has stopped is 72 hours and 30 minutes. However, in practice, it is usually closer to 3 hours.
Mailhosts.Org Shortlist Reports Shared Hosts
Host-reputation Blacklists will list either single IP Addresses that host multiple domains or entire ranges of IP Addresses from DNS &/or Email Hosts that host email for their registered domains on shared email servers. When one company sends Spam Mail or Unsolicited Bulk Email (UBE), the entire ranges can be reported as blacklisted.
Mailhosts.Org Shortlist 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)
Mailhosts.Org Shortlist 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.