Skip the "Greetings," "Salutations," "Dear sir/madam." These are far too stuffy and robotic. Instead, start off your response with a simple "Hi" or Hello."
University-wide mail services will be running a reduced schedule, accepting all mail from both postal zones and sorting; however, deliveries will be made to only a few approved locations on Main Campus. Hospital and clinical operations will not be impacted and will receive normal mail pickup and deliveries during winter break.

Changing it every evening is definitely too much, though. I would assume the vast majority of people sending business email understand the concept of working and non-working hours…
If you have critical projects that can’t wait until you return, offer a communication option like text messages, suggests Reeves. “I have found, to my delight, that people really are judicious about texting you while on vacation,” he says, with one caveat. “Don’t put your mobile number in the away message. That way, only people who have your mobile number can text you. And those are the ones you care most about.”