Hello Michael McGovern,
You are right, and the sender e-mail is hardcoded in the current versions. We will have to change this - it's now logged. The good news is that this is the case only when you send the confirmation e-mail, which means that you can still send your newsletters. When you create a newsletter, you can define the sender's name and e-mail.
We apologize for the inconvenience though, hopefully we will push this fix soon.
the Telerik team