Thought I'd share this since it can help a) prevent inadvertently sending out massive emails from your dev environment and b) help you debug the emails that are going out:
put this simple script somewhere, call it dev-mailer or dev-mailer.bash or something:
#!/bin/bash cat >> /tmp/logmail.txt
Save it, chmod 755.
Now, edit your php.ini script (use phpinfo() in a web server script or php -i from the command line to find which ones are being used).
For the "sendmail_path" configuration, change it to this:
sendmail_path = /dir/to/dev-mailer.bash
Save, restart your web server.
In a new terminal do:
tail -f /tmp/logmail.txt
I'm not sure if it works with Windows.
Hope that helps.
Found this a few years ago at http://seancoates.com/mail-replacement----a-better-hack