After doing some testing with Leopard we have found there are issues. Mail in some cases stops working and there seems to be no fix at this point to make it work again.

After a lenghthy call with Apple support they tell me that there are issues when upgrading an existing OS to Leopard in some cases. And they now say it is a documented bug that they are working to resolve.

They did say that they have had no reports of this being an issue with clean installs of the OS but I have no confirmation on that at this point.

We Will keep you posted as they work through thi sissue and post the resolution as soon as we have one.