It is recommended to upgrade any instances of Exchange 2013 to a newer version of Exchange as soon as possible. Exchange 2013 servers can also be migrated to Microsoft’s hosted Exchange Online email and calendaring solution, available as an Office 365 subscription or as a stand-alone service. Once mailboxes, public folders, and other data are migrated, admins can remove on-premises Exchange servers and Active Directory. Microsoft recently urged customers to keep their on-premises Exchange servers up to date to have them always ready for emergency security updates. On Tuesday, the company also released the February 2023 Exchange Server security updates, saying, “although we are not aware of any active exploits in the wild, our recommendation is to immediately install these updates to protect your environment.”
https://www.bleepingcomputer.com/news/security/microsoft-exchange-server-2013-reaches-end-of-support-in-april/
