As written by Microsoft today, Exchange Admins should block .NET Framework 4.6.1 which is now a recommended update on WU (Windows Update) which might be auto installed. The reason is that there are currently known issues. Microsoft also mention how to block the update. If you already have installed it check here. To check which version is already installed read the following article: "Find out which .NET Framework version is installed".
- Microsoft Exchange Server 2010 Service Pack 3 released
- Rapid growth in transaction logs, CPU use, and memory consumption in Exchange 2010 when using iOS 6.1
- Released: Update Rollup 5 for Exchange 2010 Service Pack 2
- Released: Update Rollup 3 for Exchange 2010 Service Pack 2
- Microsoft Exchange Server 2010 Service Pack 2 released