CiviCase + CiviRules + Tokens
You can do this with CiviRules. The trigger is then Case is changed. At the condition you can select Field Value Comparison to check for the right case status. 

At the action you select: Send E-mail to contacts on a case'

It might be that you need two condition with the field value comparison, one of the old case status and one for the new case status.

You need for this the CiviRules extension and the Email api extension.