Today's the day to say goodbye to our old friend, Exchange 2007. At this point you should have completed the project to move all mailboxes and resources from Exchange 2007 to a supported version of Exchange, and uninstall the Exchange 2007 servers.
Thanks to Exchange 2007 I went to MCM, and discovered just how badly Greg Taylor and accomplices can break an Exchange environment and turn it into a qual lab. I recall Greg sitting at front chomping on doughnuts as we were doing the qual lab, and in typical Greg humour posted 17 Frowns and a Box of Donuts. At the end of the day though it was all green ticky ticky!
As noted in Save The Date – End of Exchange 2007 Extended Support, Exchange 2007 introduced many new innovations, and pushed the envelope. It was the first Microsoft server product to really embrace something called PowerShell. Back then PowerShell was called Monad, and its domination was not yet determined. Exchange 2007 was the first Exchange release to ship on DVD. The high availability framework was a welcome addition for enterprises. Cluster Continuous Replication, Local Continuous Replication and Standby Continuous Replication (introduced in SP1) resolved the single copy issues from Exchange 2003. When coupled with the Outlook 2007 client, Autodiscover could create and maintain Outlook profiles. Exchange 2007 roles could be split out and installed on separate servers, and this was only fully reverted with Exchange 2016 so that we now have a single internal Exchange role to deploy.
CAS and certificates still are challenges for admins, though most of these issues are now well understood. The "fun" of deploying Outlook Anywhere at scale also became apparent with Exchange 2007 and thankfully RPC/HTTPS is being replaced with MAPI/HTTP. For some bedtime reading go and re-read the Outlook Anywhere scalability whitepaper, good times!
As always you can look at the Microsoft support lifecycle site to determine where a given product is at in its lifecycle. The below shows a search for Exchange 2007. Note that Outlook 2007 has a different end of support date compared to Exchange 2007. Outlook 2007 will exit out of extended support on the 10th October 2017.
On an un-related note, Windows Vista SP2 also transitions out of extended support today.