For testing purposes I want send mail to my localhost user account rather than my webserver. I am unsure how to do this using mail.app. Any help would be appreciated.
Unless you are running OSX Server, then there's no SMTP/IMAP/POP3 server running locally. You can get one up and running very easily using Post Fix Enabler or, if you don't mind the command line, use MacPorts to install postfix: