“The world is serious enough as it is - people need, and usually appreciate, an unexpected moment of levity in their day,” he says, when quizzed about how recipients might respond to such an OOO. He also confides that he himself has dispensed with auto responses altogether – though not for idealistic reasons. “The last time I tried to set one up, I botched it so badly that somehow it resent every single email in my outbox from the previous year - client emails, firing notices, literally thousands of emails.”
You need to let colleagues, clients, and prospects know that you won’t be available, while ensuring that they know the best course of action to take while you’re away.

Such emails are crucial, especially when you have long-lasting relationships with customers that need a prompt response. It would be very unprofessional to leave without explaining why you aren’t answering. It’s like if you are having a conversation with someone, you decide to just take off without saying goodbye, while they went to the bathroom. Rude!
Sample out-of-office email message: “Thank you for your message. The University of Toledo is closed for winter break. If your message requires a response, I will reply after New Year's Day during normal business hours. Happy holidays!”