Oh, it’s part of a much larger set of problems. He will put in the subject line “don’t read until Monday,” also not understanding that when I say I do not look at my email on my off days, I really do not see them, because I don’t open my work email out of work. And that I have a personal email account, that is not my work account?
Any correspondence (email or phone calls) sent my way will be responded to within 2–3 days of my return.

My employer uses Outlook and it has an option to display all OOO messages when you add the person into the To/CC/BCC fields of an email, prior to sending it. It’s pretty great and actually saves an email sometimes because I can see who I should contact and just go to them.
What we need in our work communication is not more professional politeness or less formal, chat-based messaging applications like Slack. We need honesty. The problem is that we’ve conditioned ourselves to see honesty as self-indulgent or disrespectful. I’d argue the opposite is true. Honesty, even if it’s a bit more inconvenient for all parties in the moment, pays dividends later. It builds trust. When my partner Anne Helen Petersen and I were interviewing people for our forthcoming book on remote work, a frequent lament from both middle managers and workers was that they didn’t feel like they knew how to succeed in their jobs; that they were guessing what their superiors and coworkers wanted and, even when they asked, they didn’t quite trust the responses they got back.