What I found to be even more relaxing is if all the employees of a company are forced to take the same time off ( 2 days to a week) and other flexible time off where the employee can choose his own time.
Then, there are no email or updates to come back to...
From my point of view, that's the way it should be. At my company we make you take vacations. If by the end of the year you have plenty of days left you tend to take a long christmas/new year's break... and in some exceptions move a couple of vacations days to the next calendar year.
The unlimited vacations days, in my eyes, creates considerable pressure/anxiety on workers. If you are in the US and want to treat employees, just go for a fair number of paid vacations days like in most European countries... Germany, France, Austria, Spain, Italy, etc, all have approx. 28 days...
Then, there are no email or updates to come back to...