A select number of users of Outlook 2013 have a problem that they cannot use the Out of Office assistant - they get a message that the server is not available. This is not all users. Exchange 2007 has all updates applied. Trying an effected user on a different PC works OK - the issue seems to be something on the PC/Outlook not Exchange server or the profile. Deleting and recreating the profile can fix the issue for a few minutes or a few seconds but the problem comes back. I cannot find any common link between the PCs, Outlook or Windows being used by the affected users vs. those that are not affected. Likewise a re-installation of Office can resolve it for a while - I have so far been unable to fix any user with the problem for any length of time. Client connections to the Exchange server are identical to those on a working machine.