Could also be described as passive moderation. The retromoderator of a group, rather than disallowing off-topic posts, will post some kind of follow-up to those posts that are off-topic designating them as such. Retromoderation is particularly popular on USENET where cancelbots are used to reduce spam. Many USENET server daemons will delete messages that have been retromoderated by cancelbots; hopefully before any human gets a chance to see them.
- Maintains some level of moderation without the bottleneck of active moderation.
- Allows readers to opt-out of moderation.
- A discussion group can be retromoderated by multiple moderators who moderate on completely different criteria (then readers can choose zero or more moderators to follow).
- Based on network speeds, messages make reach human eyes before they can be retromoderated.
- Not all servers/clients support retromoderation commands.
- Does not suffer from lysine deficiency; ie: if the retromoderator stops moderating, the spam will flow freely.