Send email to customer on case creation and closure

Hi all, I have the requirement as below:
We are utilizing only two modules: ACCOUNT and CASE (note we are not using CONTACTS). Every time we creating a case or close a case, we need the system to send a email to notify the customer that the case is being created/closed.
All accounts and cases are created/closed manually, meaning not through inbound emails or Joomla websites.

To achieve this goal, is the best practice to use WORKFLOW module? If so, then how (the problem is there is no linkage to cutomers’ email address when using CASE in workflow.) If not, what need to be done?