Help your users know when to expect a response. It’s easy to show customers your team’s availability and let them know when they can get assistance from your team. You can manage their expectations by setting your office hours and expected response time.
I’d side-eye if an OOO for a couple of days off said that, unless someone was in an unusually time-sensitive role. But if someone’s out for long enough that there’s an alternate contact provided, that’s long enough for them not to be wading through missed emails when they get back.

Note: If you are using an older version of Outlook, such as Outlook 2007, go to Tools > Out of Office Assistant.
With plenty of employees still working remotely months into the pandemic, “I actually think it’s more important now than it was before,” says Muse career coach Angela Smith. “From the perspective of how do we make remote work work,” she says, “overcommunication is one of the hallmarks.” In a world where you can’t see whether your colleagues are at their desks, being clear about when you’re working—and when you’re not—is crucial to keeping things running smoothly.