OOO (Means Out of Office) and It is OK to use 
 

Posted by Marcia Bateman on Aug 22, 2022
Marcia's Musings
I get a lot of delayed emails from members that that say, "Sorry, I was on Holiday.”
 
I can't see anyone begrudging a holiday, so set your out of office... it looks better than not replying for a week or so.