Out of Office Reply
Why is it that people think these are needed/useful? They are annoying on so many levels.
First of all, they're counterintuitive to the whole idea of email. I don't expect you to read and respond to my email instantly, it's the nature and the blessing of email.
Secondly, they're generic, meaning that most have no useful information. So what if it says, "I will be out of the office from X to Y"? Should I expect a reply on day Y+1?
Further, some of these people belong to mail lists. On a busy mail list, one getting a dozen or more emails a day, a dozen or more of these generic responses go back to the mail list. Just for one person.
Just because your email client has the capability of Out of Office replies doesn't mean you have to use it. Let's face it, you're not really that important to me, and if you were, I'd expect something more personal.