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.
In the top right corner, click the cog icon to open Outlook settings, then click “View all Outlook Settings.”

I used to work with someone who had a message telling people she only checked her email twice a day. You pretty much needed to call her if you needed anything outside of those times. (She worked in a remote office.) I think she had read one of those books on efficiency that recommended scheduled email time. But there were problems with this: 4. My department often had to email attachments or text to illustrate our questions/concerns. And we were on deadlines. Reading a page of text over the phone was not an efficient use of anyone’s time 5. She did outreach & was often out of the office on site visits, trainings, or travel to these places, but never ever set her OOO for these, because she was “working.” However, she was effectively not available to read emails from other staff until after hours on those days.
This. I’m surprised more people dont havent mentioned this, but this has always been my back to work routine – and sometimes if vacations overlapped, I’d find a summary email of “While you were away, X,Y,Z happened, I covered A, but you might want to check on B and C” which was always very helpful.