Automatic Approval of Draft Emails!

Hi , 

I have a set of emails running in a program and I would like to make some changes in the live emails and keep them as a draft.

The issue I am facing is that I want to approve the new draft emails and unapprove the existing ones and sometimes this action needs to be done during night time as well.

Is there a way we can automate the draft approval at certain time??

Urgent help would be appreciated.

Regards, 

Shweta