Getting more detail is going to be key here. Firstly you will want to check the connector to make sure it's started. If it is you can use the test e-mail button to generate a test. If it comes back successful the issue is likely with the rule configuration or something else (server is blocking the email, etc).
If you don't see a success, you will want to check the LEM Internal Events filter for an error message, a few likely candidates are covered in this article:
Email Active Response connector does not send email notifications - SolarWinds Worldwide, LLC. Help ...
