Hi Matt,
Thank you for contacting us. You can accomplish this through the "Gold" package that has the "Reseller Panel" support. It allows you to create multiple accounts and whitelabel each account. In fact, you can assign even different IPs per account. If an account has more than one IP, these will be load balanced. Some companies use this feature to separate their transactional email from marketing email. Please let us know if you have further questions.