I sent an email to colleagues today because I didn't want to forget an idea I want to pose after vacation, yet I can imagine colleagues lamenting, "It's school vacation, please don't email." I can understand that feeling. They work hard, and now it's time to rest.
Yet, you don't have to respond to an email or even read an email over vacation, and once we get back it will be so busy since we're typically on-task with students most of the time, that some do prefer to consider an idea during a leisurely breakfast or evening break rather than during the busy time-on-task days of school.
Yet, I'll curtail emails during vacation as it's only fair that people have a break. I'll keep a little file of catch-up notes to share if appropriate afterwards.
Today's thought, however, was well shared though since it's an idea that needs some time to consider.
As for email protocols, that may be a good topic of conversation sometime in the future.