Assume that you create more than 50 Microsoft Outlook rules in a Microsoft Exchange Server 2010 environment. You try to create or manage a rule by using Outlook 2013. In this situation, you receive the following error message:
The rules on this computer do not match the rules on Microsoft Exchange. Only one set of rules can be kept. You will usually want to keep the rules on the server. Which rules do you want to keep?
This issue occurs because Outlook 2013 has rules validation. This causes a mismatch of the client-side and server-side rules when there are more than 50 rules.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.