Using the "E-mail delivery" scheduled task is much like launching the E-mail Robot and having it deliver a subset of the available messages for delivery. (If the Standalone E-mail Robot is running you probably don't need to use this task.)
By using the configuration options in this task, you can have VSys deliver only specific messages. In this example, the task will only deliver letters whose Letter type is "Reminder", and then only those generated in the past half hour. This is useful to have the task deliver reminders that it just generated but not anything else.
This task only works for SMTP delivery of letters, not MAPI or SMS. Mail delivery via MAPI must be done manually. Delivery via SMS can be done with its own scheduled task.