I had some issues getting an email when folks had signed up and it was a pretty knuckleheaded deal on my part.  My web and mail servers are in two locations and I was using a web server which still had my email account's domain, active, in vpopmail.  At an earlier time that box had been both my web and mail server. This will not work, for some fairly obvious reasons (whoops).

Also, I recommend downloading the plugin below to keep people from being able to sign-up and just start posting away.....  This will require the admin to aprrove an account before it actually works.....(whoa - great idea!).  Be sure to (1) upload the thing, and, (2) enable it.....

Downloads the Registration Approval Plugin

Email Settings

There is a HUGE ERROR IN THE DIRECTIONS IMMEDIATELY BELOW! These setting used to work; however, with the implementation of new spam filerts which block PHP-sent mail at AOL, Gmail, and more you need to CHOOSE SMTP. Enter the FQDN of your mailserver in place of localhost. Choose SMTP authentication, as well (which is correct in the graphic, below).