This week's book giveaways are in the Refactoring and Agile forums. We're giving away four copies each of Re-engineering Legacy Software and Docker in Action and have the authors on-line! See this thread and this one for details.
I don't know anything about your business owner's requirement, but we use JMS queues as a step when sending emails because the queue guarantees delivery and the message is not deleted from the queue until the consumer acknowledges that the email was sent successfully. Messages can be "sent" (queued) even if the email send process is offline.
If you have an email failure, like if the network is unavailable or the email gateway goes down, how do you propose to handle it?