You can also use Outlook. Set Outlook to prompt you for a profile when it opens by closing Outlook, then going to the control panel and opening the mail icon and clicking show profiles. When you open outlook again it will give you a prompt. Click “new” and put in the mailbox of the other user. Once you have it opened as its own profile you can set or remove the out of office on their behalf. They can also set their own out of office remotely using OWA themselves. Many people do not know they can do this using OWA.