April 11, 2023 marked the official Exchange Server 2013 EOL. After that date, Exchange Server 2013 will run—but it won’t be supported by Microsoft. Microsoft will no longer offer tech support, bug fixes, time zone updates, or security patches for the software.

Continuing to use Exchange 2013 after the April 11 EOL cutoff is strongly discouraged for the following reasons:

Security: Microsoft is the most attacked vendor in the industry. After Exchange Server 2013 reaches EOL, bad actors will be looking for exploitable vulnerabilities and scanning the web for unpatched ES2013 instances to attack. Using software after EOL is, therefore, a massive security risk.

Compliance: Considering the dangers involved, using Exchange Server 2013 after April 11 raises compliance and liability issues as well. While this is something that leadership in every industry needs to be mindful of, it’s far more of a formal regulatory concern for, e.g., a hedge fund or an asset management firm.

Operations: Exchange Server underlies Outlook, so users running outdated versions of the mail server software will eventually start to see compatibility issues with their Outlook add-ins. The reason is that third-party vendors, like Microsoft itself, will no longer support ES2013 after April 11. At some point, your Bloomberg or FactSet add-ins may simply stop working!