Having spent months telling people that email is not reliable and can fail at any minute and must not be relied on, and then having to put up with the fall out when the shitty provider broke something, I can confirm that people get angry when email breaks.
"email is not reliable and can fail at any minute and must not be relied on,"
In what universe? If email were to stop working in most major corporations that I've worked in for the last 8+ years, the company would basically come to a halt.
Email, for many, many companies is the message/workflow bus, and if it stops - communication comes to a halt.
It is, after electricity, and the network, the one essential function in a company in 2013.
Telephones, Photocopiers, Printers can all cease functioning , with little impact in most technologies companies - but not email.
And yet Email is the most failureprone thing out there. It was not meant to be relied upon in the degree it is today. And yes, many companies grinds to a stop as soon as email is down. There has been no big improvements to the reliability email the last 40 years. I mean, what is the date format in email? Any sort of current standard? What date-stamp are most email readers trusting? Ever had an email that says it arrived 1997? I still get those sometimes.
I don't know where you keep coming up with that - Email is relatively easy to make highly available, and an Exchange Server in 2014, configured with even a modicum of skill, will likely keep running smoothly for the next 10 years. It's as close to 5 9s, of availability that you can get on a software system.
"There has been no big improvements to the reliability email the last 40 years. "
That's just silly. Take 5 minutes to read through http://en.wikipedia.org/wiki/Email and you'll see what improvements have been made in the last 40 years.
Deliverability of email relies on a number of factors outside your control.
You also mention competance, which is available in variable quantities. You might be able to keep Exchange 2014 running solidly, but I've seen people doing scary things with MS SBS Server 2000 (and the exchange that comes with that).
But you nail it. Had Gmail, Reddit or any other unpaid service gone down like this, the uproar would be heard from another galaxy.