Recently the support for .NET 4.61.& Exchange has changed.
The text below is a part of the Quarterly Exchange Updates published on Technet.
Support for .Net 4.6.1 is now available for Exchange Server 2016 and 2013 with these updates. We fully support customers upgrading servers running 4.5.2 to 4.6.1 without removing Exchange. We recommend that customers apply Exchange Server 2016 Cumulative Update 2 or Exchange Server 2013 Cumulative Update 13 before upgrading .Net FrameWork. Servers should be placed in maintenance mode during the upgrade as you would do when applying a Cumulative Update. Support for .Net 4.6.1 requires the following post release fixes for .Net as well.