The Senders page will allow you to edit and add a new Sender's email.
Adding a sender email address
To add a new sender to your account, you need to hover over your account name and click on Account, then click on the Senders tab. From this page, you can click on the + button and add the information.
A confirmation email will be sent to this email and will need to be verified before this email can be used to send campaigns.
Once a sender is added, it can also be deleted or edited.