Jim,
It depends on where you did the checking!
There are 3 places that you can check off "silent mode".
One is in the Standard Shield module, another is in the Internet Mail module and the other is located in the Outlook/Exchange Mail module. If you do not want any of the messages to appear, then I would insure that they are all checked especially as it relates to Outlook. Yes, the Outlook/Exchange module is all you need, but checking the others makes sure you got "them all".
Good luck.