If you want your message to be formal, avoid using contracted forms such as I’m and I’ll as well as informal or casual language. It’s also a good idea to start your message with an expression of thanks like: If your audience isn’t from your work environment, you could take a risk with something more fun and personalised:
A. No; serving students and helping to ensure their safety remain our top priorities. As with previous winter breaks, all residence halls are closed except International House and Ottawa West, with limited staff available to meet student needs, such as Front Desk employees (see the next question). Additionally, senior staff will be available to respond to any urgent student matters.

I kept it even though I received it four years ago because it made me laugh so much!
This. I’m surprised more people dont havent mentioned this, but this has always been my back to work routine – and sometimes if vacations overlapped, I’d find a summary email of “While you were away, X,Y,Z happened, I covered A, but you might want to check on B and C” which was always very helpful.