Those of us who are back in the office haven’t bothered plugging most of the phones back in. We aren’t in roles where we get phone calls, those people are still mostly WFH. There is one persistant caller who does not seem to comprehend ‘X is working from home – please email them’, but that’s the only call we ever get.
Closing Off with a Signature. First and foremost, one of the most common ways you close out a letter formally is by leaving your signature. So, if your letter is actually a hard copy, leaving some space under the end of the letter will be enough for your signature to fit.

What makes this a decent example of an OOO message is that it’s candid, (hopefully) honest, and blunt. There’s no guessing whether or not this dude is going to respond to your email this week. Also, it gives us a bit of an insight into his life right now, which helps communication in the moment and in the future. He’s burned out. Even if you did manage to reach him, it’s likely he’d be resentful, even if he didn’t say so. There’s a good chance the sender of the original email will identify with this and respect his time.
Of course, managing a minute and a half response time isn’t so easily accomplished when you’re out of office, receiving hundreds of texts each hour, or shifting your attention to a different project.