DNS Configuration

Ok here is situation, the company I work for has an outsourced company handling there email and website. They decided to bring email in house for easier management. So I have to setup the new email system, everything on my side has been worked out. Just one thing they want to keep the same domain name for email. So my question is what do I have to setup in dns since the outsourced company is still handling the company website? Or can they just redirect mail to our smtp server