Official Gmail Blog: Got the wrong Bob?

A bizarrely named new Gmail Labs feature, “Got the wrong Bob?” is intended to save you from emailing the wrong people.

If you typically add Jane Doe, Bill Smith, and John Doe to the same group message, Gmail will warn you the next time you accidentally add Bill Lumbergh instead of Bill Smith to one of these messages.

Basically, it’s another new experimental Gmail feature designed to save us from ourselves.