Legally important

Providing Disaster Recovery (DR) for Exchange servers has always had strong arguments in its favor.  As an overall requirement, being able to get the email systems, calendars and contacts back up and running ranks pretty high up the list.  But there are other reasons to look at Dynamic Infrastructure solutions for Exchange that go beyond the convenience of Exchange end-users.

When email is stored only on the production Exchange server, it can be altered or destroyed by anyone with access to that server, which means anyone with an email account that allows them to see that particular user's mailbox.  This leaves you with a whopping legal liability (check local listings on exactly what that is for you), but one that can be avoided in most cases.

Using an Operational Recovery tool, like Double-Take TimeData (see disclaimer below), will allow you to ensure that another copy of the data is not only held off-site, but held in a repository that tracks all changes to the email, calendars, contacts and all other information.  This way if a critical change is accidentally applied, or if someone maliciously attacks the data on the production server, you have the ability to revert either individual items or the entire Store or Storage Group as required.

This means that if the data is required for a legal requirement (like court-ordered discovery), you can be sure that not only will the system be available, but also that any information that could be lost without impacting the server can also be quickly and efficiently restored.  Of course, being able to get that information back to some other server or even to a desktop or laptop is best, so look for tools that give you that flexibility.  After all, if you don't happen to have the original server running to perform the restore of information, you'll need to be able to designate someplace else to receive the data instead.

This doesn't change anything you might be doing with DR and Dynamic Infrastructure in your Exchange Environment, but gives you a deeper level of protection and flexibility that most standard DR tool-sets just can't natively offer.