Raise the drawbridge, get stuff done!
The best way to deal with email is to ignore it.
Maybe read the ones from your boss, provided they weren't sent to everyone (and your boss's boss with the same proviso). Apart from that, if it's important the emailer will phone you, or come to see you to ask why you never pick up your voicemail - which brings me on to the next stage.
There are only two times of the day to read email: soon after you've got in (and had your beverage du matin) and some point shortly after lunch. Never, ever open your email within an hour of knocking-off time or you may be staying at the orifice later than you expected. It's been my observation that people who are continually glued to their email don't really have anything better to do with their days - and spend most of them sending emails to others in the same situation. Don't get drawn in to this sticky web.
Unless your job description specifically says that you are employed to deal with emailed inquiries it's a reasonable bet that most of anything you get from outside your chain of command is either irrelevant or asking you to do something that you won't get recognition (or a cost code) for. So you'll end up doing someone else's job but on your own time.
So far as sending email goes: don't. The only two reasons for emailing someone is as a CYA or to avoid phoning them. If you email someone, they're quite likely to reply. If they reply, they'll almost certainly require you to do some extra work that is not in your interest or immediate set of goals.