I've written an easy-to-use script which will load your settings from resource.cfg and send you a test email. It will also show you in the terminal the results, which may be helpful if you believe there is an error (since you'll be able to see the output of sendemail).
To run the test script:
sudo nems-mailtest email@example.com
where [email protected] is your actual recipient email address (must be different than the one you set in resource.cfg).