And if you suspect that you won’t look through all those emails that cluttered up your inbox while you were on a vacation at all? Be honest about it and tell your prospects to contact you again at a certain date.
I used to work with someone who had a message telling people she only checked her email twice a day. You pretty much needed to call her if you needed anything outside of those times. (She worked in a remote office.) I think she had read one of those books on efficiency that recommended scheduled email time. But there were problems with this: 4. My department often had to email attachments or text to illustrate our questions/concerns. And we were on deadlines. Reading a page of text over the phone was not an efficient use of anyone’s time 5. She did outreach & was often out of the office on site visits, trainings, or travel to these places, but never ever set her OOO for these, because she was “working.” However, she was effectively not available to read emails from other staff until after hours on those days.

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I’ve honestly considered changing my OOO message/voicemail to “You’ve reached Lisa. I’m overwhelmed right now, so I’ll get back to you eventually.”