People are naturally impatient, and when they are looking for answers to their questions, they want them as soon as possible. That’s why some recipients of your auto-reply messages won’t be happy if they just get some information that you are gone and have to wait for your return. In such cases, you need to provide an alternative point of contact for urgent matters.
A. International House’s front desk will be open for students 24 hours each day throughout winter break, except on the holidays – Dec. 25 and Jan. 1. However, there will be professional staff on call 24 hours a day throughout the break to adequately serve students. The Front Desk may be contacted at 419.530.1600; this phone will be answered 24/7, even when the desk is closed on both holidays.

I might sound nitpicky but the language is important. “Might” or “may be” or “slower than usual” are vague and don’t offer the sender all that much information about when you’re really going to respond to them. Worse, they do a horrible job of protecting the time of the email receiver who, as the responder notes, is not in the office! Such a responder implies that, not only will the vacationer reply to the email, but they may not even miss a beat. They may be slow to respond, but they also might not.
Unfortunately, literally every single thing in the world is an emergency in my office :(