Professionally ignore people with style.

This automated reply confirms I am unavailable, as previously implied by my calendar. I am out of office for reasons that are boring but fully valid. Last-minute revisions are still last-minute revisions even if you add a smiley face. A delayed answer is forthcoming once timing becomes less ridiculous. Immediate concerns should be sent in a single clear message and not a flurry. Thank you for adjusting to this entirely foreseeable delay.