Robert_Charlton - 3:23 am on Jan 19, 2011 (gmt 0)
Do you have failover mail servers?
I'm not a server person, but I've looked into setting up failover email enough to know that failover mail servers are extremely difficult to set up if you want to provide continuous email service.
It's much easier to use a company like DNS Made Easy to provide a shared failover mail caching server, which caches email while the main mail server is down and then sends the cached messages when the server is up and running again. The service is fairly cheap, but you'd have to do this for each of your clients individually.
DNSME also provides failover DNS services for web hosting... but you have to know how to set up backup web hosting to make use of that.
Failover email is way beyond what most web hosting companies provide, btw, and I've never heard of a design company getting into this as a service for its clients. You might as well offer to do their taxes for them too. ;)
On the other hand, if you are responsible for the emails for many companies, you're at least going to need to back things up.