The Microsoft Exchange team has issued a warning regarding .Net Framework Exchange comptability with the latest framework iteration (4.6.1) here’s an except of the post
[su_quote url=”http://blogs.technet.com/b/exchange/archive/2016/02/10/on-net-framework-4-6-1-and-exchange-compatibility.aspx”%5DWe wanted to post a quick note to call out that since yesterday, the .NET Framework 4.6.1 has been made a recommended update on WU (Windows Update). As we have already stated in the Exchange Supportability Matrix, at this time, this version of .NET framework is not supported by Exchange. In fact, we know of some issues if it is installed. We are working with the .NET team to ensure that Exchange customers have a smooth transition to .NET Framework 4.6.1, but in the meantime, delay this particular .NET update on your Exchange servers (information on how this can be accomplished can be found in the KB article 3133990, How to temporarily block the installation of the .NET Framework 4.6.1).[/su_quote]
As usual suggestion is to carefully check the Exchange Supportability Matrix when determining which version of the .Net Framework to install on the Exchange server and approve on WSUS or Configuration Manager.
If you happeened to install .NET Framework on Exchange server you can follow this article on the Exchange team blog on how to proceed with the removal and bring back your server to normal operations.