I stumble upon this topic and couldn't resist writing an answer.
My name is Daniel, and I am CEO of email startup. But I don't want to promote here, let me just tell you how I email.
I receive more than 150 messages every day and I have to reply to most of them. It's tedious. If I open email only once or twice a day I will miss too much information and I can't afford that as a CEO. So I check email whenever I can and manage it on the go. I snooze it, set reminders, archive, delete or reply on the spot if I can.
I am often in meetings or on the way, and I don't have laptop with me. But I have my phone and I can say that I email from my phone more than from my laptop. I use Gmail web interface when I am at my laptop though. Hate Outlook and Microsoft stuff.
One great thing (and bad thing) is that email is de-facto standard for business correspondence. And it has some rules, like say hi, compost long sentences, and have a signature. I hate those rules and hope they change in the coming years to resemble normal messaging (like WhatsApp). I try to stay sharp and reply in 5 sentences or less. I even wrote a blogpost about best rules for email if you want to improve your productivity.
I've been working in email field for many years now and know almost everything about human behavior, best practices and worst cases. Just ask away if you need any tips or want to know how many emails are sent everyday (190 billion emails of non-spam btw).
PS - if that post helped you, take a look at email client we created to help business people be more effective with email - Mailburn. Thanks.