My OOO is almost always “I’m out of the office and will be returning on x date.” My email sig has instructions along the lines of “for questions on x, email this list” for a couple of the more common areas people would contact me about that might need an urgent reply (as the lists go to more than just me, obviously), but most people have finally figured out to contact those lists to start with, anyway. If I were in the middle of a project or something that needed to be moved along in my absence, the project teams usually know when we’re out, but I’d put a back up in that case, if needed, but generally there’s not much to be gained by a longer OOO from me.
I will always assume it is an inability to interact in an adult fashion with the world of technology. There is no good reason to avoid voicemails so aggressively – those that are doing so should probably be seeking therapy to overcome their issues with technology and/or the human voice. A lot of us process text faster and more accurately than speech, especially poor-audio-quality speech recorded by someone who didn’t bother to leave all the relevant information. Most voice mails are bad.

Remember, your email signature is as important to your company as all of your other corporate branding. Update any marketing promotional banners with seasonal offers. When the holiday season is over and your promos have finished, make sure you are no longer using a Christmas themed banner.
If you’re going away on vacation, it’s very useful to set an automatic “out of office” reply for your emails. These automatic replies let people who email you know that you are not available to reply to their messages. Here’s how to set up an automatic out of office reply in the Microsoft Outlook desktop app and the web version.