The Management Office will be closed on [date] for [Holiday Name]. Any inconvenience caused is much regretted.
Yes, qualifiers can be helpful. Limited vs no email access, out of the office versus working off site, regular out of the office versus extended leave, etc.

Plus, he incorporated a delightful technique to let people know that if they really wanted him to read their emails, they should probably send them again after his return. Not only does that keep the sender accountable by saying, “If this is really important, you know when to reach me,” but it also helps him truly vacate his work while he’s away. And that’s hard to do. First, travel to my homeland of Florida. Climb to the highest peak of the tallest mountain. Find a rare flower (no specifics, of course… It’d be cheating). Put the flower back, because as the old hiking rule goes, “Leave everything as you found it.”
“Many people reveal details about their personal lives in an OOO — like where and when they’re traveling,” Tim Sadler, CEO of Tessian, explains in an email interview. “Whether done on social media or in an auto-reply message on email, this arms hackers with the information they need to either craft a convincing email targeted at the OOO employee or impersonate the person who is on vacation and target one of their colleagues.”