I'm a manager. I've just received a whatsapp from someone in my team who has been off sick all week. It's starts 'hi nunya, sorry for messaging outside work hours but I just...' and that's all I could see when it popped up. It's clearly work-related otherwise it would have started with more of a 'hi hun, chit chatty' vibe.
AIBU to leave it unread and open it in the morning?