It makes a positive difference when you create auto reply messages that adhere to the basic elements of personalized messages followed with greetings.
This is what I’ve seen most often in my career. Problem is, the contact is almost always the admin. I’m the admin. Everyone’s idea of assistance is different. Often, I didn’t have the knowledge about the issue in order to be of any assistance. I wound up spending more time running around looking for answers than actually working on what was on my own plate. It’s exhausting. Otherwise known as “please don’t call us for unicorn problems when we handle llamas. Literally, we can’t do anything for unicorn problems.”

One of your European connections here. When I know the person covering me will also be away for part of the time I’m gone, I get another colleague to cover for those dates and put that in my OOO. Saying “Your e-mail will not be read” or similar is really off-putting. The youth worker at my church does this and I find it infuriating. Of course it won’t. That’s the point of a holiday. When I get an answer from someone who reads his e-mails on vacation I’m pleasantly surprised.
As with all winter breaks, but especially in a longer break, division and department leaders are responsible for ensuring that external contacts are aware of the closures and as appropriate salaried staff are performing services as necessary to meet the needs of the community during the closure, including checking email/voicemail and responding to time-sensitive matters.