You can create an email account on your domain through the company where you originally registered your domain, like Godaddy.
You don’t need anything from PSMU!
As long as you completed Step #3 of the startup instructions on your PSMU Blog, all you need to do is contact your domain registrar (like GoDaddy) and have them create the email(s) that you want through their available email packages.
Moving your blog onto Practical Social Media’s blogging service does nothing to keep you from ordering email on your domain. We host your blog, but all email services always originate from your domain registrar.