by John Provasnik.
Another thing to check is that your admin has enabled email messaging from your Moodle:
Admin - Plug ins - Message Outputs - Manage Message outputs:
Then, click the Settings link for Email.
My Moodle wouldn't send any emails because I had an out of date STMP host. Once I cleared out the textbox and left it empty (which is the default), then my emails began working.