Since e-mail with classified information is in the news, can we discuss the normal process for classifying e-mail and other communications?

The media seem to bring up e-mails on a private server, and it doesn't seem to get much real attention. I also have many friends who have worked with or in the Government with classifications and this confuses me.

When you are sending email in a high-level government job, are e-mail exchanges typically classified before, after, or haphazardly?

What is the normal process for reprimanding someone who is sending e-mail, memos, or other communications that end up outside the correct classification groups?