As organizations navigate the shift from traditional on-premises infrastructure to agile cloud services, mastering both and Exchange Online has become a core requirement for IT professionals. Whether you are maintaining a legacy footprint or orchestrating a full-scale migration, understanding these "essentials" ensures a secure and efficient messaging environment. The Support Landscape: A Critical Deadline

: Using "end-of-life" software can fail regulatory audits and data protection standards.

Microsoft has officially ended support for Exchange Server 2016 and 2019 as of . Running these versions past this date introduces significant risks, including:

: Servers become vulnerable to new exploits without official patches.

Exchange Server 2016 and Exchange Server 2019 End of Support

To stay supported, administrators should either migrate to or upgrade to the newly released Exchange Server Subscription Edition (SE), which requires a subscription-based licensing model. Core Administration Essentials

Exchange Server 2016 & Exchange Online: Essentials for Modern Administration