Most techies know that e-mail, instant messaging and other Internet-borne communication is never truly anonymous. They also know that it can hang around for a long time, loitering on backup disks, mail servers and local hard drives, then popping up at the most inopportune moments.

The same is true of text messages on mobile phones. David Beckham wasn't the first person to discover that deleting something from your phone's inbox doesn't remove all traces of the message, and he's not the last, yet many people still seem to believe that electronic communications are fleeting, private and untraceable.

Now, combine this false belief with the ease with which such communications enable people to flirt, and you have a recipe for embarrassment. I hadn't thought much about this until the last half of 2004, when it emerged that several of my friends had discovered that their partners were having affairs. All of them found this out by checking their partners' e-mail accounts or mobile phones.

A dodgy practice, you might say, but the fact remains that these people (all but one of them were IT-savvy blokes) found out that their partners were playing away, and the proof was there in writing. The 'adulterers' concerned apparently didn't understand the nature of electronic communications (or, says the psychologist in me, they unconsciously or consciously wanted to be caught out anyway).

Despite my reticence to own a mobile phone, I eventually caved in last year, since when I've used text messaging to flirt like a unashamed monkey. I've sent and received a few steamy e-mails in my time, too. I think that flirting's good for everyone, regardless of whether or not they're in a relationship. It improves your self-esteem, spices up your private life and generally makes you feel happier. As long as it goes no further and you're honest and fair about it, there's no harm done.

But if it does go further, the evidence is there for anyone to read. Deleting e-mails from your account does nothing; they're still floating around waiting for someone with sufficient technical knowledge to track them down. Ditto text messages. And if you have an itemised phone bill, that's yet another piece of evidence.

Technology has made it far easier for people to wander out of relationships, but it's also made it far easier for any indiscretions to be discovered. So please flirt safely, and remember that the 'delete' button won't save you.