This is the situation with pretty much every free service irrespective of who provides them. What we need to realize is that free services, let it be email, web hosting or something else, are not the solution to all the problems and needs we have. This is particularly true in a business environment. Before you go ahead with these free services, do take some time to assess the cost of using them:
How important are those free services you rely on?
How does the unavailability of services affect you and your customers?
Cost of unavailability vs. Cost of paid service?
What alternative sources are available to augment free services you are using?
How does the response time affect you?
It's always healthy not to rely on free services for your important and primary services. I am not completely ruling out the use of services like free mails - they are great for certain things but not for everything. In fact, I will continue to keep all developer/user mailing lists I have subscribed to under Gmail.
I hope someone will come up with a really cool mail service which leverages on existing free mail services like Gmail, Yahoomail and Hotmail. A naive example would be, we get an email address and the actual email is replicated in the three major mail provider accounts which will dramatically reduce the cost of relying on one free email. (Gmail does allow to forward a copy to some other account while keeping a copy, but I am thinking of something that will work even in the face of unavailability and I am not considering the possibility of manually setting up a forwarding list through a paid service)