You have the ability to resend a message(s) that has already been processed and delivered. To do this, select the Resend Batch button in the Send Messages box on your portal.
You will be provided with a list of your recent sends. You are able to drill down each item in order to receive additional information regarding the past send details.
To resend a message, simply select the Resend button and a confirmation page will populate with the send details.