Mass Deleting Scheduled and Sent Mailings, Drafts, etc
This does not exist in the UI currently. However, it does seem like a good idea to have a script that deletes OR archives mailings that are greater than N months / years old. So i'd recommend writing a api job that does the needful.

Approx steps would be:

a. Create a new delete/archive mailing job taking parameters like list of ids or mailing delivered before date XXX

b. Check and ensure that the mailing delete api deletes all the right tables. Most of the deletion is done by mysql via cascaded relationships. At a quick glance, the api delete does not seem to handle file attachments

c. Use the API from item b to implement the scheduled job

Please do share your extension so others can benefit