Thanks Ross. I think the most helpful information I found was this:
http://stackoverflow.com/questions/16830673/wamp-send-mail-using-smtp-localhost
One of the answers shows links to 5 different methods. Very helpful. I chose the 'fake sendmail' method since I saw logic in the oxwall/php_mailer/ow_libraries/class.phpmailer.php file that checked for the path of sendmail in /usr/lib. The logic seemed to indicate that if it found /usr/lib/sendmail, oxwall would use it to send email. However, it doesn't seem to be working. When it comes time to send an email (when a user joins, for example), it will hang indefinitely 'waiting for localhost'. I know that the sendmail program is working because I'm able to send successfully from a php script I put together for testing, but it's not working from oxwall.
If anyone has been down this path before, and got it working, I'd really appreciate it if you could point me in the right direction. Local install, Windows 8, WAMP stack. Thanks!