You know that you can add Google Analytics code to your emails very easily. That works really well, but the URLs generated with the Google parameters can sometimes cause issues.
They’ve written up in quite a bit of detail how they worked around the problem using some smart .htaccess rewrite rules. If you are seeing the same issue, make sure you check it out.
Read Using URL rewrites to make ExpressionEngine, Campaign Monitor & Google Analytics play nice over at the Newism blog.