So a user goes on holiday and either sets the wrong OOO or doesn’t set one at all. Previously I would have reset the users password, logged in as them and then set it correctly. Not a brilliant solution, but it works.
In Exchange 2010 it’s a lot easier. Just like logging into OWA, you can login to ECP (Exchange Control Panel) by going to https://owa.domain.com/ecp. From here you can select any user and change various settings, including their OOO messge.
Simples. Oh, and if you get an “Invalid Canary” error when searching for users (yes, you read that right, one of the more random error messages I’ve seen) check that the /ECP/ in the URL is in lowercase and this will fix it.