Scheduled Building Power Outage

I a couple of weeks the building we are in is having to do some repairs to the electrical system. Our power will be shut down for at least 12 hours. I plan on shutting down the servers just before they start. But management has come to me saying they want our email to still be flowing since 90% of our business is done via email. Now I was thinking of moving there server off site but that means alot of configuration changes, right? Are there any other alternatives out there that I can explore? Or are they out of luck during this time? Thanks.