Google Labs is offering an interesting Gmail add on - Mail Googles - designed to prevent users of the free mail service sending messages they might later regret due to inebriation.

Gmail engineer Jon Perlow states: "Gmail can't always prevent you from sending messages you might later regret, but today we're launching a new Labs feature I wrote called Mail Goggles which may help".

The feature presents would-be emailers with capchta-style maths puzzles before it will send the email, but only at more likely times:

"By default, Mail Goggles is only active late night on the weekend as that is the time you're most likely to need it. Once enabled, you can adjust when it's active in the General settings."

Perlow says: "Hopefully Mail Goggles will prevent many of you out there from sending messages you wish you hadn't. Like that late night memo - I mean mission statement - to the entire firm..."