import org.springframework.security.core.userdetails.UserDetailsService;

public class MyUserServiceImpl implements UserDetailsService{

    @Autowired
    private AdminUserDao dao;

    @Override
    public UserDetails loadUserByUsername(String email) throws UsernameNotFoundException, DataAccessException {

    ... Here comes your logic to get your the user based on email

    }
}

<authentication-manager>
    <authentication-provider user-service-ref="myUserServiceImpl" />
</authentication-manager>

<authentication-manager>                                                                                                     
	<authentication-provider>                                                                                                   
		<jdbc-user-service data-source-ref="dataSource"                                                                            
			users-by-username-query=                                                                                                  
				"SELECT email,password,enabled FROM users WHERE email=?"                                                                 
			authorities-by-username-query=                                                                                            
				"SELECT u.email, ur.role FROM users u INNER JOIN user_roles ur ON u.user_id=ur.user_id WHERE u.email =?  " />            
	</authentication-provider>                                                                                                  
</authentication-manager>