nattu,
One possibility is to use the "Run Keyword If Test Passed" and "Run Keyword If Test Failed" keywords in your teardown.
Ex:
Run Keyword If Test Passed SendPassEmail
Run Keyword If Test Failed SendFailEmail
Where in SendPassEmail and SendFailEmail keywords you send the email
I have never sent an email in a keyword but you could try this lib
here are example from the source code
Another possibility, would be to implement a tool / script that parse the xml test result and send email.
xml schema is documented.
Regards