Who owns your old email messages?

Over in our Forums section, a member named The Chief has asked for clarification on this: "if a member of staff leaves a company, is the email address that he was using (eg joebloggs@mycompany.com) owned by him or the company?"

It's an interesting question. If your former employer doesn't shut down the address, they could scan for any interesting titibits in emails from your contacts. These, in turn, are imagining they are talking to you, and might be less guarded than if they knew they were being read by Big Boss.

What do you think? Has anyone had any experience of this, either good or bad?