Although I don't use Outlook for Mac to access corporate email which is touched by Enterprise Vault any longer, I do still try to use my Mac to read mails with Outlook, and from time to time still point Outlook at one of my test environments which has EV involved. So in keeping up to date with the happenings in Enterprise Vault + Mac + Outlook, I spotted the following technote which talks about an issue with Outlook 2011 SP 3. Take a look to see if you are likely to be affected:
http://www.symantec.com/docs/TECH209123
