This is why I turn on the 'out of office auto reply'.
You aren't the only one.
Not there yet, but looking forward to it. The trick is to put the vacation message up *before* one reveals any major grades (even the ones for individual assignments). I tend to be a softie (as well as being realistic about my ability to screw up) and promise (and complete) a quick check-in or two for truly urgent queries before I disappear before the holidays, but I *will* disappear from Christmas to New Year's. Even if I could or would change their grades (I won't, unless there's an actual mistake), it can't be accomplished until the registrar is back from winter break. And most discussions of grades benefit from a substantial cooling-off period in between emails, I find. If there really is something to address, we'll do it in January (and if it's my mistake, they'll get a prompt promise that I will address it in January, and follow-through on that promise, but I'm not spending winter break discussing why Bs aren't B+s, B+s aren't A-s, and so on).