Dear Mac Manners,

I've done a terrible thing. We have two Justins in our office--Justin G. and Justin K.--and I sent a catty message regarding Justin G.'s floral spats to Justin K. Or so I thought. Somehow my message went to Justin G. and not Justin K., and now I can't face Justin G. in the lunchroom. What have I done?

Shamefaced in Shiloh

Dear Shamefaced, You've been betrayed by your e-mail client's Autofill feature--which automatically fills in a recipient's address as you type a name into an e-mail message's To field. This is a wonderfully convenient feature--most of the time. But as you've discovered, it can cause a message to go to the wrong recipient if you're not careful.