It is astonishing how quickly my email drops off when the undergraduate are on break (currently, study break before finals). Engineering at GiantU has a general email list, plus I'm on my departmental list, the graduate students in my department list, and general university-wide sorts of emails. All of this results in a fairly large volume of email during the semester, much of which is completely irrelevant to me. And because there are often typos, it can be challenging to effectively filter out the crap.
To top it off, GiantU is having a major spam problem of late. In an average day, I probably get 30-50 emails. Of these, I care about 3-5... which means ~90% of the email I receive is irrelevant. However, during breaks, it's much closer to half.
What changes your email volume?