I will be out of the office starting (Starting Date) through (End Date) returning(Date of Return). If you need immediate assistance during my absence, please contact (Contacts Name) at (Contacts Email Address). Otherwise, I will respond to your emails as soon as possible upon my return. What is the best out of office message?
We do it every time we go on vacation or take a sick day. We put up an out-of-office (OOO) message with the date of our return, a colleague’s contact information for urgent needs, and maybe even some details about the destination of our long-awaited vacation.

I appreciate your attempt to connect with me today, but unfortunately I am no longer available at this email, or organization.
There’s a grim, apologetic vibe to these messages — I’m sorry I’m taking time for myself but I’ll try to check in on occasion! They’re a vivid reflection of a work culture that valorizes constant productivity and the near-total overlap of work and life. But they’re also do a terrible job of what they’re intended to do, e.g., set realistic expectations for both sender and recipient. A vague OOO message traps both parties in an uncomfortable liminal space where both productivity and rest go to die. The original sender is left unsure if they’ll be getting a timely response or a whether the email will go ignored for a time or forever. The original recipient has taken what is a rock solid excuse (time off) and cheapened it, offering a backdoor for email guilt to creep in.