Microsoft has announced Period 2 of the Exchange Server 2016/2019 Extended Security Update (ESU) program. This extension provides continued access to security updates for legacy on‑premises Exchange environments, but it should be viewed strictly as a temporary risk mitigation measure. While ESUs extend time, they do not extend safety nor help avoid inevitable #MSExchange https://xf.ms/Ex20192016ESU2
Announcing Period 2 Exchange 2016/2019 Extended Security Update (ESU) program | Microsoft Community Hub

We created a Period 2 ESU for Exchange customers who need extra time to migrate to Exchange SE.  

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