When creating a Task in Solomon you can tell the system to send an email once the task has been marked as 'done'.
Within the Create a Task window you can select to send notifications and enter the email into that field. Once someone has marked the task as complete an email will automatically be generated.
Once sent, the 'Notifications Sent' toggle will be marked 'Yes'. This prevents any further notifications being sent. You can also manually set this.
If you'd like to learn more about creating a task click here.