“Ideally, an OOO should include the basics,” says work and wellbeing psychologist Kate Sullivan. “The dates you'll be gone, an approximate timeline for when someone can expect to hear back from you upon your return, and how any urgent requests will be handled in your absence.”
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.

Thank you for your email. Our offices are closed until [date]. If it’s something you need urgent assistance, Contact [Name] on [phone number] or [Email]
2.) Herzlich willkommen bei Mustermann GmbH. Aufgrund unseres Betriebsurlaubes sind unsere Servicemitarbeiter erst wieder ab Montag, den 04.07.2016 für Sie erreichbar. Der Versand der Bestellungen wird ab dem 11.01.2016 wieder starten. Gerne können Sie uns aber in der Zwischenzeit Ihr Anliegen per Email an [email protected] oder über unser Kontaktformular zukommen lassen. Vielen Dank!