The system doesn't send the offer letter to the candidate until the workflow is approved and processed. For example, even if you are a high level manager and you select a workflow that has no approval steps, you still need to wait for the workflow to process. Once the workflow is approved and processed, the system automatically sends out the offer letter to the candidate.
When an offer letter is pending workflow approval, you cannot cancel or edit any part of it from the Recruiting module. You need to wait for the workflow to process. As will be shown later in this entry, you can rescind the offer, but only once the system processes the workflow and sends the offer to the candidate.