We have had problems both with our own Exchange server and with another client’s this morning. Sophos released a Support Advisory last night and the KB article is here: http://www.sophos.com/support/knowledgebase/article/42245.html To resolve the problem we tried restarting the PureMessage services, the Sophos Services and the Exchange Services but the only thing that really seems to have solved it is rebooting the SBS box...... Hope that might help someone else.....