Just because something doesn't necessarily need a response immediately doesn't stop it being important, or urgent. Much of the time support people might be busy with something, and so an urgent problem goes to e-mail. Personally I use e-mail rather than a phone call when I need a response because I'm aware that people are often away from their desks or using the phone.
First thing to remember is there is no such thing as a very urgent email if something is so dire that needs a response right now you will get a phone call or someone will visit you.
My own phone is in use most of the time, and e-mail means that I can continue to communicate with people when I need to. Multitasking is a very useful school, and generally I can help resolve several relatively simple but important problems via e-mail while investigating the highest priority one by phone.
Not only that but during investigation you may need documents, or other attachments, or you may need to send utilities. E-mail's the easiest and quickest way to do this. Try sending an error log by phone.
Finally, if you need to tell 100 people the same simple message (for example to tell them about an urgent outage on your MIS server) then phoning really isn't the best way to do it.
Would've been much easier to send a mass e-mail, wouldn't it?
Think back to last time school got the call from Ofsted most schools try to keep quite and have everyone at one meeting to announce it.
How many people came up to you in that day and said "have you heard Ofsted are due in but keep it under hat as not meant to know yet."
How exactly was the meeting itself announced?
The outage apparently lasted about 100 minutes for some users. If its your own e-mail server, then at least its everyone in your organisation who's affected. Everyone's aware of the problem. With something like gmail going down it affects a lot more people than just, say, a school e-mail server going down. Some of those people are going to be relying on their e-mail for orders, support, urgent communications and so on.
It was down for about 30 mins for me.. if that and lets be honest if your email server went down good chance it would down for longer than that.
I don't necessarily agree with some of the complaints, I'm strongly of the opinion that you get what you pay for, but I can certainly understand why they're complaining.
Its not necessarily about survival as such. E-mail going down is a huge inconvenience for me. It means that work stacks up a lot more, I'm unable to deal with simple problems which come through which otherwise could be resolved with a quick e-mail. It makes my life a lot harder in other words, even if I can still continue.
Sorry if you can;t survive with out your email for 30 minutes then you really need to look at your email management techniques.