There are a million reasons why people feel the need to sheepishly telegraph that they’ll be checking email while OOO: a toxic workplace culture; a set of bad managers who don’t model work/life balance or use manipulative tactics like saying, ‘feel free to take some time if you need it’; companies that are so focused on lean growth they don’t have anyone to pick up the slack when an employee opts to take time off. These days, merely having the confidence to step away from your job by taking the vacation time granted to you in the terms of your employment agreement is still a privilege in the American workforce.
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.

If it’s anything less than a business day, it just becomes this extra beacon of our completely toxic and out of whack work culture that insists we be reachable every second.
Therefore, if your email truly is urgent and you need a response while I’m on vacation, please forwarded it to my personal email [email] and I’ll try to respond to it promptly. If you think someone else at [company] might be able to help you, please contact [name] at [email] or [phone], and they’ll try to point you in the right direction. Otherwise, I’ll respond when I return.