I worked at a public agency and would have different out-of-office messages for internal and external. I was chastised for having a “too informal” message- because the idiot talking to me didn’t realize me saying “I’ll be back next Tuesday for the big staff meeting” (or whatever) was just for co-workers and not the public. I told them but of course it didn’t matter. So from then on I always made sure to start my internal OOOs- “Hello Company X comrade…. blah.” So it was clear which was which. I am not able to respond to your email promptly because my husband died. I will not be accepting zoom invitations. Please do not respond by suggesting future alternative dates. I don’t know when I will be able to speak without crying.
Every November without fail, when I take a week off for deer season, I start my OOO with “GONE HUNTIN’!”

I am on annual leave until dd/mm/yyyy. I will allow each sender one email and if you send me multiple emails, I will randomly delete your emails until there is only one remaining. Choose wisely. Please note that you have already sent me one email.
When you are not in the office for more than a day, telling people who contact you that you might not be checking or responding to your emails right away will help them complete work in your absence. Setting up an out of office message can help you communicate this information. This article will describe how to write an out of office message and provide examples of effective message formats.