Hi! Will we use lot of the CAS server performance if all you aes clients are proxied from exchange 2010 instead of redirected? Brian

All depends on what your users are doing and your environment. If this post helps to resolve your issue, please click the "Propose as Answer" If you find it helpful , mark it as helpful by clicking on "Vote as Helpful" button at the top of this message. By marking a post as Answered, or Helpful you help others find the answer faster. If you need an expert migration consultant to assist your organization feel free to contact me directly. Jason Sherry | Blog | Hire Me | Twitter: @JasonSherry Microsoft Infrastructure Architect, MCSE: M, MCTIP, Microsoft Exchange MVP

You can know more information about proxy and redirection from this document: Understanding Proxying and Redirection http://technet.microsoft.com/en-us/library/bb310763.aspx Thanks, EvanEvan Liu TechNet Community Support