Leaked emails show Yahoo’s new CEO talks tougher than her geeky, mild-mannered predecessor. And that any email, any time, can be leaked.

The lady talks tough. In among her first comments to staff, incoming Yahoo CEO Carol Bartz (an internet newbie who comes to the company from 3D architectural software company Autodesk; left, looking sweet and innocent), told the troops she would “drop kick to f**king Mars” anybody responsible for a leak.

Those comments were, of course, leaked.

And this week, her first rallying-call email to staff was leaked, too.

There are technologies out there to stop leaks.

One example: a Microsoft rep showed me how the latest versions of Exchange and Outlook can work with Windows Server to control email.

Using the three Microsoft products in concert, you can set whether than heavy-duty memo can be printed, forwarded internally, or forwarded outside the building.

However, one of the company’s own clever-clogs techies was equally quick to find a workaround, opening a restricted email on a notebook, then photocopying the laptop’s screen on one of those new-fangled all-in-ones that sends the scan straight to your computer.

And as Bill Gates discovered, subpoenas can also extract email.

For true security, follow the post card test: if you wouldn’t write something on a post card, don’t send it in an email.

Make that dodgy comment over the phone.

Or, if you’ve got something sensible or legal to say, attach it in a password-protected Word document (there is encryption software out there, but it’s too fiddly to use).

Of course, I don’t follow these rules myself.

But, be warned.