The Slack messaging feature allows users to unsend messages under certain conditions, such as within a 15-second time frame and without any subsequent actions. Users can also delete messages permanently, but this action is irreversible and may be difficult to track down if someone has already seen the message. Additionally, there are options for editing or automating Slack messages using features like Zapier's integrations with other apps, which enable users to automate tasks and workflows across their organization.