The sendmail plugin is a low level plugin used to manager emails.

The plugin can break down a list email address in a set of registered users (this uses a signal that the mailinglist plugin implements.) It then saves those emails in each user's mail account. Finally, it runs a backend process that will actually email the message to the user as defined in the user's schedule.

The sendmail does not have its own user interface since it is very low level (i.e. the users plugin is using the sendmail plugin and thus sendmail cannot be using the editor plugin.)