This post is a list of Microsoft Exchange versions, build numbers, Update Rollups and Cumulative Updates that I keep up to date.
The latest version is Exchange 2019 CU2 which was released on 18 June 2019.
Microsoft Technet has some really useful articles at the links below detailing all the Exchange Service Pack and Update Rollup build numbers since Exchange 2003.
Since this page was first created Microsoft has now combined the two source pages itself into one Exchange Server Updates: build numbers and release dates page which can be found at the link below.
The tables below are a snapshot of the link as of June 2019.
Edit: Update Rollup 18 is now available for Exchange 2010 SP3 see the post Exchange 2010 SP3 Update Rollup 18 installation tips.
Microsoft have just released the latest round of Update Rollups for Exchange 2007 and 2010.
Microsoft last week released two new Rollups for Exchange 2007 SP3 and Exchange 2010 SP2.
Both were released on the 13th August and contain a number of fixes.
Exchange 2007 SP3 Rollup 8 can be found here.
Exchange 2010 SP2 Rollup 4 can befound here.