Still, although you'll find plenty of "honest out-of-office reply" spoofs on the Internet, honesty is in the eye of the sender and recipient.
For what it's worth, after 20 years of working in offices, here's what I think the truly most honest out-of-office replies look like:
Thanks for your message! I am out of the office until Thursday. If you're using Microsoft Outlook (and you probably are), you likely saw that pale green auto-fill thingie telling you precisely that in advance of you hitting send, thereby begging the question why you chose to hit send anyway. If you need immediate assistance, please find someone whose name comes up in black and not green.
Thanks for your message! I'm out of the office on personal leave, and won't be checking email. That is a lie. I will be checking email every ten minutes because the thought of things happening at work without me gives me a heart attack and crippling anxiety. Also, my extended family is making me insane. Unless this email is about carpet cleaning or time sheets, you can expect a response within 30 minutes. Thank you for the excuse to escape from my vacation.
Thanks for your message! I literally had to take the day off from work to clean my house. You wouldn't believe how disgusting it is. There are still cold scrambled eggs on the floor from yesterday! Can you believe it? If this is a so-called urgent matter, please call my cell phone at (123) 456-7890 and I will promptly attend to your so-called urgent matter in order not to have to fold a mountain of laundry.
Thanks for your message! Am I cc:d or bcc:d on this email? If so, could it not have waited? Why are you doing this to me? Does this happen in Europe? I've heard Germany has like, an actual law against off-hours work emailing. That said, my insecurity, responsiveness, and lack of personal boundaries all but assure a response to your email within the hour.
Thanks for your message! If you look at your iPhone you will see that it's sunny in Juneau so good luck reaching anyone in cell range, much less me. I will reply to your email when the monsoons return 12 hours from now.
Thanks for your message! My kids are home with Pink Eye, which means they aren't allowed to be in school, but still feel well enough to make me crazy. I'll respond to your email sometime between monitoring the crumbling of the Republic in real time on Twitter and breaking up a fight over whose turn it is to play Crossy Roads on the iPad.