If those weren’t bad enough, if anyone on that lists sets up an out-of-office message, it *automatically* replies all. If the email bounces back, it bounces back reply all. One guy left the company and his email had a permanent out-of-office auto reply. The list was quite busy for a month or so and the message popped up multiple times a day.
Every business is unique. There’s no one single best way to tell your clients that you’re not going to be around for the next few days (weeks or months). But there’s also no denying that whatever out of office message you use right now, you could always improve it.

For many roles, of course, the sort of OoO described wouldn’t work. But there are a lot of roles where people would survive just fine letting their requests sit for an extra week before forwarding again. And especially at smaller companies where there they might be pressed for coverage when people are out, I think it’s great to normalise that a job is basically ‘off-line’ for a week or two so that the employee can rest and recharge.
I work in a role where someone else has to cover when I’m out, so most things do get taken care of. I have never been in a position where I could delete all emails without ruffling some serious feathers, so while I appreciate the motivation, it’s a completely foreign option to me.