Hello, and thanks for your email! If you’re getting this message, it means I’m taking my annual two-week creative sabbatical—working on personal projects that inspire me, so that I can return to work full of fresh ideas for my clients, like you! I’ll respond to your note once I return to the office on [DATE]. In the meantime, here’s a question: What inspires you? Do that, today.
That’s what I always reasoned… better to annoy with too much information that saves hassle on the backend then be brief upfront and sentence people to OoO purgatory.

I’ve had several co-workers over the years use “at my earliest convenience” and it’s always rubbed me the wrong way. It just sounds kind of dismissive like, “I don’t care when you need it, I’ll get to it when I get to it.”
Unfortunately, I’m going to have to return your message. As it’s the holiday season, I’m currently away from the office. When I return, I’ll give your email a good solid read and find that your request is exactly what I needed after all! But until then, I’m going to keep it in the inbox so it doesn’t get damaged and revisit it after the holidays are over.