Fuck. Let them be pissed off. The beauty of read receipts is that you have proof that at least they opened the damned thing. However you go, just keep stuff that you think you might need or even stuff you don't and archive it, back that shit up and call it good.
Be as handsome as possible. Female superiors will look at you as fresh meat. Hello, mysteriously early promotion! Two words: boob graze. Makes the day pass better. Make sure the glass is thick enough to support your weight before Xeroxing your taint. If a guy has a black office chair, splash chili death sauce on it when he goes to lunch. It dries fairly clear and despite it being dry, it will eventually make him feel like his chestnuts are TRULY roasting once he sits on it for a bit and his body heat moistens it up. This is a very cruel thing to do, so make sure you hate him right away it being your first day. Make fun of the janitor that brings in his kids to lessen the work load for himself.
When you are new, keep your mouth shut and listen to other people. Don't be that new guy with all sorts of ideas to improve the business. There may or may not be a time for management to consider what you have to say, your first 90 days is not the time. Get access to your corporate email account either at home or on your phone. Reading your email before and after work will prepare you for the next day or can help put out any fires that may arise. Also, read the complete email thread all the way to the end as it may answer some of the questions you may have. I started working before email was prevalent and learned that sarcasm doesn't really work all that well in email and is not appreciated by your coworkers. Another thing I learned to do is to wait a few minutes before responding to a bitchy email with one of my own.
Most email programs I've used give you the option to decline sending the read receipt. I never send them, because I don't want some jerk off seeing when I've read his email, ignored it for half the day, and replied when I felt like it. Many people expect you to drop everything for them when they demand it - fuck them, I've got 20 things on my plate at any given time. I agree and disagree. While I'd say, yes, shut up while you find your footing, to not suggest improvements within your first 3 months is a bit much. Big companies are rife with inefficiency, all the time. Bosses should be encouraging good suggestions. Not that it matters much anyway, because most of the time "it's just policy" and you won't make a difference until you're higher in the chain.
Suggesting improvements at any time is a good thing, but for the love of god if someone who's been there a while tells you no, whether the reason seems good or not, let it go. If you press on and ask for a better explanation or keep saying why your idea needs to be implemented you will, at best, be looked at as a pompous prick, at worst as insubordinate. It's a tough pill to swallow (it certainly was and still sometimes is for me), but as a young guy fresh out of college all those 'ground breaking ideas' you have to improve the company have probably already been thought of and failed for reasons you cannot yet understand. So when someone discards your idea, move on. After you have some real experience under your belt you'll be more likely to have solid ideas that people will take seriously.