As my tech associate Tony Redmond said on his blog, http://windowsitpro.com/blog/lots-exchange-premises-updates-install, “Lots of Exchange on-premises updates to install.” He is right, Microsoft just released updates to Exchange 2007, 2010, 2013, and 2016 today! Not many environments are running all four, but I know of many that are running 2010 mainly and have started to migrate to 2013, but have now switched to 2016 so they have all three versions running in their enterprise.
2016 CU1 & 2013 CU12 will both update the AD schema, so coordinate with you AD team before attempting to install.
The updates to 2007 and 2010 includes security improvements, mainly changing S/MIME to use SHA-2 vs. SHA-1.
The CU1 download for Exchange 2016 is an ISO and future CUs will probably be also, it’s also very large at 6.4GB vs. 2013 CU12 at 1.7GB. Since it’s an ISO you will need to mount or extract the files to install 2016 CU1.
2016 CU1 and 2013 CU12 both remove the mailbox anchoring support added in CU11 and 2016 RTM. See Tony’s post here on what the issues were with this: http://windowsitpro.com/blog/exchange-mailbox-anchoring-runs-stormy-waters.
.NET Framework 4.6.1 still should NOT be used on Exchange 2013 and 2016 servers, another post from Tony on this topic: http://windowsitpro.com/blog/exchange-says-no-net-framework-461. We hope this is resolved in the next CUs for 2013 & 2016!