We've got a very unusual issue. Since yesterday, ALL of our Macs are unable to connect to Exchange 2007. There's an average of around 20 Macs, some on Snow Leopard, some on Lion. None are able to get emails and it doesn't matter whether it's on Outlook 2011 or 2008.
However, all the PC's are able to get emails. Webmail is also working!
We haven't installed any updates on the server which Exchange sits on either.
What gives? Could this be some sort of certificate problem?