An Email Protection Gateway (EPG) is a security component that sits between external senders and internal mail systems. It inspects, filters, routes, quarantines, and logs messages so organizations can enforce email policy before mail reaches users. Because it is in the mail path, an EPG often has privileged visibility and control over traffic, authentication, and message handling.
This matters in cyber security because an EPG is a high-value target: if attackers can exploit it, they may tamper with mail flow, weaken filtering, or gain a foothold inside a trusted control point. Common attack paths include code injection, where untrusted input is processed as executable logic. Defenders should treat EPGs like critical infrastructure: patch them quickly, verify updates on the device, review administrative access, and monitor for unusual requests or changes in mail policy. A compromised gateway can affect many users at once, so its security directly shapes the trustworthiness of the whole email environment.