Manual:Email

Here are some ways of troubleshooting email.

Error sending mail: Unknown error in PHP's mail function Mediawiki
Put the following into LocalSettings.php, making the necessary substitutions for yourEmailAccount and yourEmailPassword:

Then install the packages required to send the mail.

After this you may get an authentication failure type error. You will need to sign into the gmail account you are using and verify that the person that just signed in is you. You only need to verify this one time. (gmail will send you an email and you just follow the instructions)