Something like, “I will not have access to email while I am out and will get back to you when I return. If your issue is urgent, please resend your email after X date,” would be… more polite, I guess.
Agree that part time staff was odd to include here. I have no idea if you are part time. I don’t keep track of other people’s schedules. I would find it helpful to know you aren’t available the rest of the day in case I need something sooner.

There ought to be a word - and perhaps there is, in German - for the mix of feelings that accompanies composing and activating a holiday out-of-office message. There's smugness, of course, and a gratifying sense of laying down one's virtual tools after a horribly long shift. But for many of us, these nice feelings are tempered by the knowledge that in two weeks, refreshed but depressed, we will have to trawl through hundreds of emails, many of which will be conference room notifications for meetings about crises that have passed.
I absolutely hate this and it would definitely irritate me if received. I agree with the letter writer that it comes over as condescending and also a bit passive agressive in places. I’m definitely not the audience for this one! Presumably this is an internal only version and the company culture would find this cute / funny.