I received one from a coworker in middle management that said something to the effect of “I’m working on a large-scale project and will be unable to answer email until X date. Please contact [direct report’s email] with any questions.” This went on for well over a month.
5.) Sehr geehrte Kunden, unser Büro ist vom 24 Dezember bis zum 2.Januar nicht besetzt. Sie erreichen uns wie gewohnt ab Montag den 5. Januar. Wir wünschen Ihnen und Ihrer Familie ein frohes Weihnachtsfest und ein gutes und erfolgreiches neue Jahr.

I think important context here is that no matter what the details added were, it always had this aggressive tone of “I’m taking a break and breaks are IMPORTANT”. Which I agree with, but it felt like it was almost aggressive/accusatory, and more importantly: this person was without a doubt the meanest, cruelest, least understanding and empathetic person I’ve ever worked with who ran her staff into the ground with urgent demands and expectations.
I used to work with someone who had a message telling people she only checked her email twice a day. You pretty much needed to call her if you needed anything outside of those times. (She worked in a remote office.) I think she had read one of those books on efficiency that recommended scheduled email time. But there were problems with this: 4. My department often had to email attachments or text to illustrate our questions/concerns. And we were on deadlines. Reading a page of text over the phone was not an efficient use of anyone’s time 5. She did outreach & was often out of the office on site visits, trainings, or travel to these places, but never ever set her OOO for these, because she was “working.” However, she was effectively not available to read emails from other staff until after hours on those days.