https://www.bleepingcomputer.com/news/microsoft/microsoft-exchange-server-2013-reaches-end-of-support-in-9-months/

Microsoft has reminded customers that the Exchange Server 2013 mail and calendaring platform will reach its extended end-of-support date roughly nine months from now, on April 11, 2021.

Released in January 2013, Exchange Server 2013 entered its ninth year of service and has already reached the mainstream end date more than four years ago, on April 10, 2018.