Too Much Email:

Cal Newport linked to an Adobe study that concluded average users check email 5.6 hours per weekday. If you look into the study a bit further, it looks like these numbers are inflated but even cutting them in half, 2.3 hours a day on email is too much.
Historically, I always thought of myself as that guy who answered all of his email. It wasn’t until I realized the cost of that self-image in terms of my personal productivity, my relationship with my family and my clients, and my simple ability to ship interesting products that I was able to abandon that particular hangup.
A big help for me was time blocking email. (Hooray for hyper-scheduling!) I have about 40 minutes in the morning and 20 minutes in the late afternoon blocked for email. On days that I stick to those numbers, I generally get a lot more work done.
Maybe this week you should keep track of how much time you spend with email. If you’re spending hours a day in your email client and don’t have a really good reason for that, start thinking about ways to lower that number.

(Via MacSparky)
I block schedule email, Slack, and other as “open loops” in my calendar, typically two or three times in my work day. Email filters help hugely, as my employer sends a number of informational yet un-actionable newsletters.
Even then I triage my emails. Lotus Notes, my employer’s email platform of choice, has a delightful feature where it indicates your inclusion: a full circle means it is sent to you, a 75% means to you and others, 50% means you are in copy, and an empty circle means you are on blind carbon copy. I could be wrong on the details, but I am unaware of another mail client that offers something similar.
As for triaging Slack, anything sent to me in a Direct Message gets my attention. After that, I know what channels I want to spend time perusing. 
As for notifications and alerts, they are turned off by default. Messages from people I define as VIPs get to alert me. Everything else can wait for my attention, which I value. I value yours, too, so I will not usually message trivialities.
For more, check out Your email habits should be considerate, not just productive from Quartz.

Be nice with what you write.