Also, you need to know your audience if you are going to go eccentric. Alison mentions that this message is fine in their culture, but it wouldn’t npbe appropriate for my somewhat formal field. And even if your workplace in general is casual, you might be contacted by someone outside. (In a tiny provincial courthouse I served in the past, there is a story going around that in the 80s a junior but elderly clerk used to address phone callers as hun and sweetheart and generally speak very informally. Most people thought it was funny, and then the President of Supreme Court called and… he didn’t).
Yeah, announcing you were going to delete emails unread and expecting the sender to resend when you return would NEVER fly in my office. I’d get executive complaints about that, especially if it went to a client or outside party – if a client can’t reach you, they will reach out to someone else who may not work at your organization and you lose business. I feel like this delete-it-all philosophy would only work for an entirely internal role where timelines are more relaxed, and even then, I feel it’s a bit unprofessional to foist your own catch-up work onto others, especially if they’ve been backfilling for you while you were OOO.

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