Afer Reply / Replyall activity of an email its not redirecting back to parent module

We are creating cases from an inbound email handler. to reply an email we create a custom button in detail view. which redirect us to the detail view of an unread email. After replying that particular email its redirecting us to the email inbox. but we want it to redirect us to the parental module {case / case record}. Any suggestions how to achieve this task.