These are the colour alpha-numeric figures that potential users of free services on the Web are asked to use, to identify they really a human bean, and not a bot.
MessageLabs says that hackers are now coding bots that can achieve a 30 per cent success rate when it comes to signing up for GMail accounts, giving them a whole new range of email addresses to play
The anti-spam security firm says it spotted this fact after seeing the amount of spam originating from Google accounts as having doubled during February to 2.6 per cent of spam mail processed.
It's a lot worse on Yahoo Mail, though, as MessageLabs says that the service accounts for 88.7 per cent of the spam it processes.
Now that IS a lot of spam...