Update Rollup 12 for Microsoft Exchange Server 2010 Service Pack 3 (SP3) was released on December 15, 2015.
Microsoft released Update Rollup 12 for Exchange Server 2010 Service Pack 3 (KB3096066). The Exchange Server 2010 update includes a DST update as well as a collection of important fixes.
From the Microsoft Exchange Team blog:
This update fixes the issues that are described in the following Microsoft Knowledge Base article:
This update also includes new daylight saving time (DST) updates for Exchange Server 2010 SP3. For more information about DST, go to Daylight Saving Time Help and Support Center.
You have to update in the following order to avoid issues.
1. Client Access Server(CAS). You have to install in Internet-Facing CAS Server first. If you have deployed CAS Array, have to update in each server by disabling connections in Load Balancer(HLB/NLB).
2. Hub Transport Server(HUB)
3. Unified Messaging Server(UM)
4. Mailbox Server(MBX)
5. Edge Server(EDGE)