1) Go to the email module and create a email domain patrickmcdougle.is-a-geek.com
2) Create a mailbox for email@example.com
3) Go to the website module and create a website patrickmcdougle.is-a-geek.com.
4) create a subdirectory "webmail" in this website and install there a webmail application of your choice.
Please be aware that almost all external servers will block your system for sending email as it has a dynamic IP address. So you might have to configure postfix to relay any outgoing mails trough a external mailserver.