Gmail – create a filter that prevents sending certain emails

Gmail filters apply to sent mail by default. They do, however, not apply to drafts.

So, Jacob's answer describes the default process for making filters and it will indeed also work for mails sent by yourself.

All sent items from within Google Apps are signed like this:

example@example.com (Google Drive)

If you search for those items in the search field like this:

you can either:

1. Select them manually, to do what ever you want;
2. Prior to searching, you can create a filter.