The ever-widening scandal that took down David Petraeus as the head of the CIA started simply enough when Paula Broadwell, with whom he was having an affair, clicked the "send" button on her email program.

The resulting catastrophic upheaval, or tempest in a teapot (depending on how you see it, which is not relevant to the discussion here), has had many Americans re-examining something they may have taken for granted: their use of email and just how secure and private their messages are -- or aren't.

It's a question that obviously occurred to Petraeus and Broadwell, who took at least one action to protect their communications from prying eyes: They created a shared email account in which messages could be read and written without actually being sent.

Each had access to the account and could write messages, but rather than hit "send" each would put the messages in the "draft" folder to be read by the other.

It's a tactic sometimes used by terrorists and pedophiles, but is of little use once an investigation zeroes in on the account holders, as happened when the FBI got involved after Broadwell did, in fact, hit "send" to fling a harassing email at Jill Kelley in Florida.

Could they have done more? Can anyone take more sophisticated actions to protect the contents of an email as it zips around cyberspace through networks and servers on its way to the intended recipient?

Data encryption is an option, and there are many programs out there that will encrypt an email message to make it unreadable by anyone except the person for whom it is intended.

One of the most popular is a program called PGP, for Pretty Good Privacy, which encrypts the message that can then only be unlocked by the recipient using a private "key" of characters previously agreed upon by sender and recipient.

That may be more than something with which most of us would bother unless, of course, we're trying to hide evidence of an extramarital affair.

And consider this: Since the Petraeus-Broadwell affair has already raised concerns about national security, what would the FBI have made of it had they discovered heavily encrypted messages between the two?

So most of us are likely to go on using email "in the clear."

Are our digital communications safe? Secure? Private?

Generally, yes. At least for most of us, most of the time, for most of our messages.

But if someone legally or illegally wants to read over your shoulder badly enough, no.

If the FBI presents your Internet service provider with a warrant and asks for access to your email, your secrets will come out.

Best security strategy? Don't put secrets in emails.

Or, to recast an old maxim in 21st century terms, don't put anything in an email you wouldn't want your mother to know.