Determine the email and Code of employee who are working at United State, state MA
code of employee refers to employeeNumber; United States of America refers to country = 'USA';
SELECT T1.email, T1.employeeNumber FROM employees AS T1 INNER JOIN offices AS T2 ON T1.officeCode = T2.officeCode WHERE T2.state = 'MA' AND T2.country = 'USA'